Pub Date : 2016-07-02DOI: 10.1080/0144235x.2016.1203533
N. Heine, K. Asmis
Cryogenic Ion Trap Vibrational Spectroscopy of Hydrogen-Bonded Clusters Relevant to Atmospheric Chemistry (International Reviews in Physical Chemistry, 2015, Vol. 34, No. 1, 1–34) Nadja Heine and Knut R. Asmis* Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany; Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstrasse 2, D-04103 Leipzig, Germany
{"title":"Cryogenic Ion Trap Vibrational Spectroscopy of Hydrogen-Bonded Clusters Relevant to Atmospheric Chemistry (International Reviews in Physical Chemistry, 2015, Vol. 34, No. 1, 1–34)","authors":"N. Heine, K. Asmis","doi":"10.1080/0144235x.2016.1203533","DOIUrl":"https://doi.org/10.1080/0144235x.2016.1203533","url":null,"abstract":"Cryogenic Ion Trap Vibrational Spectroscopy of Hydrogen-Bonded Clusters Relevant to Atmospheric Chemistry (International Reviews in Physical Chemistry, 2015, Vol. 34, No. 1, 1–34) Nadja Heine and Knut R. Asmis* Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany; Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstrasse 2, D-04103 Leipzig, Germany","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"30 1","pages":"507 - 507"},"PeriodicalIF":6.1,"publicationDate":"2016-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85122719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-07-02DOI: 10.1080/0144235X.2016.1200347
B. Jiang, Jun Li, Hua Guo
With advances in ab initio theory, it is now possible to calculate electronic energies within chemical (<1 kcal/mol) accuracy. However, it is still challenging to represent faithfully a large number of ab initio points with a multidimensional analytical function over a large configuration space, which is needed for accurate dynamical studies. In this Review, we discuss our recent work on a new potential-fitting approach based on artificial neural networks, which are ultra-flexible in representing any multidimensional real functions. A unique feature of our neural network approach is how the symmetries, particularly those associated with the exchange of identical atoms in the system, are enforced. To this end, symmetry functions in the form of symmetrised monomials that satisfy a particular type of symmetry possessed by the system are used in the input layer of the neural network. This approach is rigorous, accurate, and efficient. It is also simple to implement, requiring no modification of the neural network routines. Its applications to the construction of multi-dimensional potential energy surfaces in many gas phase and gas–surface systems as surveyed here.
{"title":"Potential energy surfaces from high fidelity fitting of ab initio points: the permutation invariant polynomial - neural network approach","authors":"B. Jiang, Jun Li, Hua Guo","doi":"10.1080/0144235X.2016.1200347","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1200347","url":null,"abstract":"With advances in ab initio theory, it is now possible to calculate electronic energies within chemical (<1 kcal/mol) accuracy. However, it is still challenging to represent faithfully a large number of ab initio points with a multidimensional analytical function over a large configuration space, which is needed for accurate dynamical studies. In this Review, we discuss our recent work on a new potential-fitting approach based on artificial neural networks, which are ultra-flexible in representing any multidimensional real functions. A unique feature of our neural network approach is how the symmetries, particularly those associated with the exchange of identical atoms in the system, are enforced. To this end, symmetry functions in the form of symmetrised monomials that satisfy a particular type of symmetry possessed by the system are used in the input layer of the neural network. This approach is rigorous, accurate, and efficient. It is also simple to implement, requiring no modification of the neural network routines. Its applications to the construction of multi-dimensional potential energy surfaces in many gas phase and gas–surface systems as surveyed here.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"64 1","pages":"479 - 506"},"PeriodicalIF":6.1,"publicationDate":"2016-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90475815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-06-27DOI: 10.1080/0144235X.2016.1195102
R. Dawes, S. Ndengué
Recent developments in single and multireference electronic structure methods and the approaches suitable to generate ab initio data that may be employed in the construction of global molecular potential energy surfaces are reviewed. The most appropriate, robust, accurate and cost effective strategies are discussed in the context of various applications ranging from cold collisions and weakly interacting clusters, to large amplitude motion in covalently bound molecules, as well as reaction and photodissociation dynamics. The relationships between the types and necessary quantity of ab initio data, and representations through fitting are important, and issues related to symmetry and electronic state degeneracy are mentioned. The impacts of limitations or error in the electronic structure data are discussed in terms of how they are reflected in calculations of spectroscopy, dynamics and kinetics. This discussion includes examples such as the submerged reef feature found along the path to formation of ozone on several published potentials. For that example, a relatively small absolute error in the form of a spurious barrier has profound effects on the dynamics and rates of exchange reactions. The origin of the spurious barrier in ozone and other systems is discussed from an electronic structure standpoint. The effective use of dynamically-weighted state-averaged multireference calculations to obtain robustly convergent global surfaces is detailed.
{"title":"Single- and multireference electronic structure calculations for constructing potential energy surfaces","authors":"R. Dawes, S. Ndengué","doi":"10.1080/0144235X.2016.1195102","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1195102","url":null,"abstract":"Recent developments in single and multireference electronic structure methods and the approaches suitable to generate ab initio data that may be employed in the construction of global molecular potential energy surfaces are reviewed. The most appropriate, robust, accurate and cost effective strategies are discussed in the context of various applications ranging from cold collisions and weakly interacting clusters, to large amplitude motion in covalently bound molecules, as well as reaction and photodissociation dynamics. The relationships between the types and necessary quantity of ab initio data, and representations through fitting are important, and issues related to symmetry and electronic state degeneracy are mentioned. The impacts of limitations or error in the electronic structure data are discussed in terms of how they are reflected in calculations of spectroscopy, dynamics and kinetics. This discussion includes examples such as the submerged reef feature found along the path to formation of ozone on several published potentials. For that example, a relatively small absolute error in the form of a spurious barrier has profound effects on the dynamics and rates of exchange reactions. The origin of the spurious barrier in ozone and other systems is discussed from an electronic structure standpoint. The effective use of dynamically-weighted state-averaged multireference calculations to obtain robustly convergent global surfaces is detailed.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"4 1","pages":"441 - 478"},"PeriodicalIF":6.1,"publicationDate":"2016-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73203581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-06-23DOI: 10.1080/0144235X.2016.1192262
F. Weinhold, C. Landis, E. Glendening
Natural bond orbital (NBO) analysis is one of many available options for ‘translating’ computational solutions of Schrödinger’s wave equation into the familiar language of chemical bonding concepts. In this Review, we first address the title questions by describing characteristic features that distinguish NBO from alternative analysis methodologies (e.g. of QTAIM or EDA type) and answering criticisms that have been raised in specific chemical applications. We then address the general ‘usefulness’ of NBO analysis in the context of widely accepted philosophical criteria, including (i) broad consistency, both internally and with respect to known experimental data, (ii) multi-faceted predictive capacity, including numerical model predictions of specific properties, general correlative and statistical regression relationships, and ‘risky’ falsifiable predictions of previously unknown chemical phenomena, and (iii) general pedagogical value, promoting organisation, unification, and orderly rationalisation of chemical knowledge. Specific chemical topics chosen for discussion include controversial H⋯H ‘bond lines’ in bay-type hydrocarbon species; carbene ligation of coinage metals; resonance-type bonding of noble gas hydrides; NBO descriptors in Hammett-type quantitative structure-activity relationships; nature of conventional and ‘anti-electrostatic’ hydrogen bonding interactions; multi-centre bonding in ‘aromatic’ , Lewis-like hybridisation picture of non-VSEPR geometry and high-order multiple bonding in transition metal species; resonance origin of the ‘18e rule’; and localised (symmetry-independent) prediction of Jahn–Teller effects in free radical chemistry. We conclude with hints of some directions for future extensions of NBO methods.
{"title":"What is NBO analysis and how is it useful?","authors":"F. Weinhold, C. Landis, E. Glendening","doi":"10.1080/0144235X.2016.1192262","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1192262","url":null,"abstract":"Natural bond orbital (NBO) analysis is one of many available options for ‘translating’ computational solutions of Schrödinger’s wave equation into the familiar language of chemical bonding concepts. In this Review, we first address the title questions by describing characteristic features that distinguish NBO from alternative analysis methodologies (e.g. of QTAIM or EDA type) and answering criticisms that have been raised in specific chemical applications. We then address the general ‘usefulness’ of NBO analysis in the context of widely accepted philosophical criteria, including (i) broad consistency, both internally and with respect to known experimental data, (ii) multi-faceted predictive capacity, including numerical model predictions of specific properties, general correlative and statistical regression relationships, and ‘risky’ falsifiable predictions of previously unknown chemical phenomena, and (iii) general pedagogical value, promoting organisation, unification, and orderly rationalisation of chemical knowledge. Specific chemical topics chosen for discussion include controversial H⋯H ‘bond lines’ in bay-type hydrocarbon species; carbene ligation of coinage metals; resonance-type bonding of noble gas hydrides; NBO descriptors in Hammett-type quantitative structure-activity relationships; nature of conventional and ‘anti-electrostatic’ hydrogen bonding interactions; multi-centre bonding in ‘aromatic’ , Lewis-like hybridisation picture of non-VSEPR geometry and high-order multiple bonding in transition metal species; resonance origin of the ‘18e rule’; and localised (symmetry-independent) prediction of Jahn–Teller effects in free radical chemistry. We conclude with hints of some directions for future extensions of NBO methods.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"50 1","pages":"399 - 440"},"PeriodicalIF":6.1,"publicationDate":"2016-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73706369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-06-02DOI: 10.1080/0144235X.2016.1187006
J. Prakash, R. Harris, H. Swart
The unique physical and tunable optical properties of noble metal nanoparticles (NPs) provides the opportunity to develop new sensing platforms with enhanced capabilities in the specific detection of a variety of small molecules. While noble metal NPs are interesting as nanomaterials, future and practical applications as high-performance novel functional materials will require the use of these NPs embedded in suitable host materials. This review details how embedded noble metal NPs and the local environment influence the sensing properties for potential application in nano-biotechnology, ultrasensitive chemical and biochemical detection by surface enhanced Raman scattering (SERS) nanotechnology. Although the synthesis and potential applications of noble metal NPs based SERS substrates have been reviewed previously, there is a growing interest in synthesis and functionalisation of embedded noble metal NPs and their applications as SERS substrates. This topic has been rarely reviewed in literature. In particular, we review the highly active solid and thin film SERS substrates such as polymer and glass substrates embedded with noble metal NPs. We also discuss their optical properties due to the localised surface plasmon resonance and enhanced local electromagnetic field which are responsible for enhanced SERS activity with emphasis on their fundamental and technological applications. This review also includes a new class of promising porous coordination polymeric SERS substrates (a metal-organic framework) embedded with noble metal NPs. The review first explains many fundamental key concepts of SPR and SERS enhancement as well as factors affecting these properties in the case of embedded NPs. This then summarises methods for the fabrication of highly reproducible and robust SERS substrates embedded with NPs followed by their SERS application in detection of several chemical and biological molecules. The article also describes the recent developments in the fabrication of these SERS substrates embedded with noble metal NPs from conventional chemical routes to physical methods including novel ion beam techniques.
{"title":"Embedded plasmonic nanostructures: synthesis, fundamental aspects and their surface enhanced Raman scattering applications","authors":"J. Prakash, R. Harris, H. Swart","doi":"10.1080/0144235X.2016.1187006","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1187006","url":null,"abstract":"The unique physical and tunable optical properties of noble metal nanoparticles (NPs) provides the opportunity to develop new sensing platforms with enhanced capabilities in the specific detection of a variety of small molecules. While noble metal NPs are interesting as nanomaterials, future and practical applications as high-performance novel functional materials will require the use of these NPs embedded in suitable host materials. This review details how embedded noble metal NPs and the local environment influence the sensing properties for potential application in nano-biotechnology, ultrasensitive chemical and biochemical detection by surface enhanced Raman scattering (SERS) nanotechnology. Although the synthesis and potential applications of noble metal NPs based SERS substrates have been reviewed previously, there is a growing interest in synthesis and functionalisation of embedded noble metal NPs and their applications as SERS substrates. This topic has been rarely reviewed in literature. In particular, we review the highly active solid and thin film SERS substrates such as polymer and glass substrates embedded with noble metal NPs. We also discuss their optical properties due to the localised surface plasmon resonance and enhanced local electromagnetic field which are responsible for enhanced SERS activity with emphasis on their fundamental and technological applications. This review also includes a new class of promising porous coordination polymeric SERS substrates (a metal-organic framework) embedded with noble metal NPs. The review first explains many fundamental key concepts of SPR and SERS enhancement as well as factors affecting these properties in the case of embedded NPs. This then summarises methods for the fabrication of highly reproducible and robust SERS substrates embedded with NPs followed by their SERS application in detection of several chemical and biological molecules. The article also describes the recent developments in the fabrication of these SERS substrates embedded with noble metal NPs from conventional chemical routes to physical methods including novel ion beam techniques.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"263 1","pages":"353 - 398"},"PeriodicalIF":6.1,"publicationDate":"2016-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77045790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-02DOI: 10.1080/0144235X.2016.1148450
T. Chu, Bai‐Tong Liu
The interaction between hydrogen donor and acceptor molecules, known well as hydrogen bonding, forms a ubiquitous network in the natural and synthesis world. The hydrogen bonding role has thus been the subject of intensive work in the past. In this article, we discuss and show how the new mechanisms have been established in terms of the hydrogen bonding changes by reviewing some of the combined experimental and theoretical studies that have recently shed light on the intricate role of both triplet and singlet excited-state hydrogen bondings in photoinduced liquid dynamics and phenomena.
{"title":"Establishing new mechanisms with triplet and singlet excited-state hydrogen bonding roles in photoinduced liquid dynamics","authors":"T. Chu, Bai‐Tong Liu","doi":"10.1080/0144235X.2016.1148450","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1148450","url":null,"abstract":"The interaction between hydrogen donor and acceptor molecules, known well as hydrogen bonding, forms a ubiquitous network in the natural and synthesis world. The hydrogen bonding role has thus been the subject of intensive work in the past. In this article, we discuss and show how the new mechanisms have been established in terms of the hydrogen bonding changes by reviewing some of the combined experimental and theoretical studies that have recently shed light on the intricate role of both triplet and singlet excited-state hydrogen bondings in photoinduced liquid dynamics and phenomena.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"14 1","pages":"187 - 208"},"PeriodicalIF":6.1,"publicationDate":"2016-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81058188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-02DOI: 10.1080/0144235X.2016.1179002
L. Campbell, M. Brunger
Collisions with electrons from several sources are common throughout planetary atmospheres. While in most circumstances direct electron impact is less significant than solar radiation, electron collisions have a major influence on the chemistry driven by both photon and particle impact. This review addresses electron collisions in atmospheres, with emphasis on cases where electron impact drives, enhances, or otherwise interacts with chemical processes. Understanding of atmospheric processes typically involves computational simulation based on theory, remotely-sensed atmospheric data, atomic and molecular physics data and chemical reaction rates. These and the modelling techniques will therefore also be covered. An example of current and future work on electron impact on the hydroxyl radical (OH) is presented, where applications in both atmospheric studies and plasma medicine are important.
{"title":"Electron collisions in atmospheres","authors":"L. Campbell, M. Brunger","doi":"10.1080/0144235X.2016.1179002","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1179002","url":null,"abstract":"Collisions with electrons from several sources are common throughout planetary atmospheres. While in most circumstances direct electron impact is less significant than solar radiation, electron collisions have a major influence on the chemistry driven by both photon and particle impact. This review addresses electron collisions in atmospheres, with emphasis on cases where electron impact drives, enhances, or otherwise interacts with chemical processes. Understanding of atmospheric processes typically involves computational simulation based on theory, remotely-sensed atmospheric data, atomic and molecular physics data and chemical reaction rates. These and the modelling techniques will therefore also be covered. An example of current and future work on electron impact on the hydroxyl radical (OH) is presented, where applications in both atmospheric studies and plasma medicine are important.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"22 1","pages":"297 - 351"},"PeriodicalIF":6.1,"publicationDate":"2016-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86529744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-02DOI: 10.1080/0144235X.2016.1171039
M. Herman, T. Foldes, K. Didriche, C. Lauzin, T. Vanfleteren
The literature on the high-resolution spectroscopic investigation of molecular complexes containing small polyatomic species excited in their vibrational overtones is reviewed. They turn out to be complexes containing acetylene, ammonia and water, mainly excited in their 2CH, 2NH and 2OH vibrations, respectively. The majority of results published on these systems was obtained using an instrumental set-up based on cw-cavity ring-down spectroscopy, built in the ‘Laboratoire de Chimie quantique et Photophysique’ at the ‘Université libre de Bruxelles’ (CQP/ULB) and named FANTASIO+, which is described. It allowed retrieving upper state vibrational predissociation lifetimes, which are highlighted together with more results. The sequence of experiments at CQP/ULB prior and along the line of those supporting the investigation of molecular complexes is briefly illustrated.
{"title":"Overtone spectroscopy of molecular complexes containing small polyatomic molecules","authors":"M. Herman, T. Foldes, K. Didriche, C. Lauzin, T. Vanfleteren","doi":"10.1080/0144235X.2016.1171039","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1171039","url":null,"abstract":"The literature on the high-resolution spectroscopic investigation of molecular complexes containing small polyatomic species excited in their vibrational overtones is reviewed. They turn out to be complexes containing acetylene, ammonia and water, mainly excited in their 2CH, 2NH and 2OH vibrations, respectively. The majority of results published on these systems was obtained using an instrumental set-up based on cw-cavity ring-down spectroscopy, built in the ‘Laboratoire de Chimie quantique et Photophysique’ at the ‘Université libre de Bruxelles’ (CQP/ULB) and named FANTASIO+, which is described. It allowed retrieving upper state vibrational predissociation lifetimes, which are highlighted together with more results. The sequence of experiments at CQP/ULB prior and along the line of those supporting the investigation of molecular complexes is briefly illustrated.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"17 1","pages":"243 - 295"},"PeriodicalIF":6.1,"publicationDate":"2016-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82162459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-02DOI: 10.1080/0144235X.2016.1166830
T. Schmidt
Resonance-stabilised hydrocarbon radicals serve as reaction intermediates in flames, plasmas, atmospheres and interstellar space. Their stability is conferred by delocalisation of the radical electron through a conjugated -system. As such, they tend to have low-lying electronic states which engender a rich optical spectroscopy. Over the last sixty years, and intensively over the last decade, the spectra of a great many such radicals have been measured, ranging from three to 17 carbon atoms. The excitation wavelengths of transitions to the first excited states of these radicals range from the ultraviolet to the near infrared, spanning the visible region. In this review, the electronic spectroscopy of the various chromophores presented by resonance-stabilised radicals is reviewed. The theoretical methods used to predict the excitation spectra of resonance-stabilised radicals is critically evaluated, and two emergent rules-of-thumb are demonstrated which allow one to empirically predict the approximate excitation energy of certain radicals.
{"title":"The electronic spectroscopy of resonance-stabilised hydrocarbon radicals","authors":"T. Schmidt","doi":"10.1080/0144235X.2016.1166830","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1166830","url":null,"abstract":"Resonance-stabilised hydrocarbon radicals serve as reaction intermediates in flames, plasmas, atmospheres and interstellar space. Their stability is conferred by delocalisation of the radical electron through a conjugated -system. As such, they tend to have low-lying electronic states which engender a rich optical spectroscopy. Over the last sixty years, and intensively over the last decade, the spectra of a great many such radicals have been measured, ranging from three to 17 carbon atoms. The excitation wavelengths of transitions to the first excited states of these radicals range from the ultraviolet to the near infrared, spanning the visible region. In this review, the electronic spectroscopy of the various chromophores presented by resonance-stabilised radicals is reviewed. The theoretical methods used to predict the excitation spectra of resonance-stabilised radicals is critically evaluated, and two emergent rules-of-thumb are demonstrated which allow one to empirically predict the approximate excitation energy of certain radicals.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"9 1","pages":"209 - 242"},"PeriodicalIF":6.1,"publicationDate":"2016-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72898023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-02DOI: 10.1080/0144235X.2016.1147144
M. Shahid, C. Fan, R. Pashley
This paper presents a review of the bubble column evaporator (BCE) and its many novel applications. The BCE process offers a continuously produced source of high air–water interface and consequently provides high overall heat and mass transfer coefficients. Although the bubbling process itself is both simple to use and apply, our understanding of the fundamental physical and chemical principles involved is surprisingly limited and there are many issues yet to be explained. Recently the process has been used to develop new methods for the precise determination of enthalpies of vaporisation (ΔHvap) of concentrated salt solutions, as an evaporative cooling system, a sub-boiling thermal desalination unit, for sub-boiling thermal sterilisation, for low temperature thermal decomposition of different solutes in aqueous solution and for the inhibition of particle precipitation in supersaturated solutions. These novel applications can be very useful in many industrial practices, such as desalination, water/waste water treatment, thermolysis of ammonium bicarbonate (NH4HCO3) for the regeneration in forward osmosis and refrigeration related industries. The background theories and models used to explain the BCE process are also reviewed and this fundamental knowledge is applied to the design of BCE systems and to explain recently explored applications, as well as potential improvements. Many other prospective applications of the BCE process are also reported in this paper.
{"title":"Insight into the bubble column evaporator and its applications","authors":"M. Shahid, C. Fan, R. Pashley","doi":"10.1080/0144235X.2016.1147144","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1147144","url":null,"abstract":"This paper presents a review of the bubble column evaporator (BCE) and its many novel applications. The BCE process offers a continuously produced source of high air–water interface and consequently provides high overall heat and mass transfer coefficients. Although the bubbling process itself is both simple to use and apply, our understanding of the fundamental physical and chemical principles involved is surprisingly limited and there are many issues yet to be explained. Recently the process has been used to develop new methods for the precise determination of enthalpies of vaporisation (ΔHvap) of concentrated salt solutions, as an evaporative cooling system, a sub-boiling thermal desalination unit, for sub-boiling thermal sterilisation, for low temperature thermal decomposition of different solutes in aqueous solution and for the inhibition of particle precipitation in supersaturated solutions. These novel applications can be very useful in many industrial practices, such as desalination, water/waste water treatment, thermolysis of ammonium bicarbonate (NH4HCO3) for the regeneration in forward osmosis and refrigeration related industries. The background theories and models used to explain the BCE process are also reviewed and this fundamental knowledge is applied to the design of BCE systems and to explain recently explored applications, as well as potential improvements. Many other prospective applications of the BCE process are also reported in this paper.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":"2012 1","pages":"143 - 185"},"PeriodicalIF":6.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73700349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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