A picosecond infrared spectrometer covering nearly the whole fingerprint region has been constructed. The infrared absorption spectrum of electronically excited 4- dimethylamino-4′-nitrostilbene, which has an intramolecular charge-transfer character, has been recorded. The observed infrared intensities are generally very strong (molar absorption coefficients as high as 3×103 mol-1 dm3 cm-1). The infrared spectral pattern of the excited species is similar to that of the Raman spectrum. It is suggested that such features can be explained in terms of strong vibronic coupling in the observed excited species. Polarization measurements have also been performed.
{"title":"Picosecond Transient InfraredSpectroscopy of 4-Dimethylamino-4′-Nitrostilbene in the FingerprintRegion","authors":"H. Okamoto, M. Tasumi","doi":"10.1155/1999/75834","DOIUrl":"https://doi.org/10.1155/1999/75834","url":null,"abstract":"A picosecond infrared spectrometer covering nearly the whole fingerprint region has been constructed. The infrared absorption spectrum of electronically excited 4- dimethylamino-4′-nitrostilbene, which has an intramolecular charge-transfer character, has been recorded. The observed infrared intensities are generally very strong (molar absorption coefficients as high as 3×103 mol-1 dm3 cm-1). The infrared spectral pattern of the excited species is similar to that of the Raman spectrum. It is suggested that such features can be explained in terms of strong vibronic coupling in the observed excited species. Polarization measurements have also been performed.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"349 17‐18","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113956015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
KrF–laser-induced fluorescence from CF2-radicals was investigated during photolysis of CF2Cl2 and CF2HCl by 193 nm laserlight. In contrast to other publications, which postulated single-vibronic-level fluorescence, the fluorescence is caused by excitation from four closely situated absorption bands. These fluorescence bands of four series, are assigned to Ã1B1(v′1,6−2v′1,0) − X˜1A1(v″1,v″2,0) transitions with Δv1=0 and 0 ≤ v″2 ≤ 30. The Franck – Condon factors of the Ã1B1 (0, 6, 0) –X˜1A1 (0, v″2, 0) transitions, the frequencies of the bending vibration (ω″2 =673± 2cm–1) and the anharmonicity constants x″22 = –0.94 ± 0.08 cm-1 and x′22 = –0.44 ± 0.10 cm–1 were more precisely determined. For the first time higher anharmonicity constants are evaluated with x″12
{"title":"Laser Induced Fluorescence From CF2 Excited at 248 Nm","authors":"G. Wlnkelmann, R. Kuhls, R. Osmanow, E. Linke","doi":"10.1155/1993/56828","DOIUrl":"https://doi.org/10.1155/1993/56828","url":null,"abstract":"KrF–laser-induced fluorescence from CF2-radicals was investigated during photolysis of CF2Cl2 and CF2HCl by 193 nm laserlight. In contrast to other publications, which postulated single-vibronic-level fluorescence, the fluorescence is caused by excitation from four closely situated absorption bands. These fluorescence bands of four series, are assigned to Ã1B1(v′1,6−2v′1,0) − X˜1A1(v″1,v″2,0) transitions with Δv1=0 and 0 ≤ v″2 ≤ 30. The Franck – Condon factors of the Ã1B1 (0, 6, 0) –X˜1A1 (0, v″2, 0) transitions, the frequencies of the bending vibration (ω″2 =673± 2cm–1) and the anharmonicity constants x″22 = –0.94 ± 0.08 cm-1 and x′22 = –0.44 ± 0.10 cm–1 were more precisely determined. For the first time higher anharmonicity constants are evaluated with x″12","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114761153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two binary mixtures of ultraviolet laser dyes in p-dioxane solution are described. The tuning curve of each mixture spans more than 30 nm of useful tuning range in the 340–380 nm wavelength region. Both mixtures are robust with half-lives comparable to, or in excess of, associated single dye values. These mixtures degrade symmetrically with dye laser operation, making them useful throughout the entire life of the mixture. A simple model for the mixture lasing, based on independent fluorescences of the component dyes, is able to semi-quantitatively match the tuning curves of the dye mixtures. The results presented should be easily extendable to other dye mixtures.
{"title":"EXCIMER PUMPED DYE MIXTURES FOR THE WAVELENGTH REGION 340-380 nm","authors":"D. Landis, D. J. Schneider, C. Seliskar","doi":"10.1155/LC.11.63","DOIUrl":"https://doi.org/10.1155/LC.11.63","url":null,"abstract":"Two binary mixtures of ultraviolet laser dyes in p-dioxane solution are described. The tuning curve of each \u0000mixture spans more than 30 nm of useful tuning range in the 340–380 nm wavelength region. Both \u0000mixtures are robust with half-lives comparable to, or in excess of, associated single dye values. These \u0000mixtures degrade symmetrically with dye laser operation, making them useful throughout the entire life of \u0000the mixture. A simple model for the mixture lasing, based on independent fluorescences of the component \u0000dyes, is able to semi-quantitatively match the tuning curves of the dye mixtures. The results presented \u0000should be easily extendable to other dye mixtures.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124374852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By using laser multiphoton ionization and a time-of-flight mass filter, we have detected nascent UF5 from the 266 nm laser photodissociation of UF6, following a single laser firing. The method can be used to monitor these species under conditions wherein isotopically selective excitation is responsible for the dissociation of UF6.
{"title":"“Single Shot” Laser Multiphoton Ionization Detection of UF5 Followingthe 266 nm Photodissociation of UF6","authors":"J. S. Chou, D. Sumida, M. Stuke, C. Wittig","doi":"10.1155/LC.1.1","DOIUrl":"https://doi.org/10.1155/LC.1.1","url":null,"abstract":"By using laser multiphoton ionization and a time-of-flight mass filter, we have detected \u0000nascent UF5 from the 266 nm laser photodissociation of UF6, following a single laser firing. \u0000The method can be used to monitor these species under conditions wherein isotopically selective excitation is responsible for the dissociation of UF6.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127881036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The photoionization process of pyrene in non-polar solvent has been investigated using a two-color two-photon ionization technique. The ionization spectrum near threshold of pyrene in n-hexane was measured by a delayed irradiation of a dye laser 20 ns after an N2 laser at total excitation energies of 5.9–6.22 eV. The two-photon ionization threshold of pyrene was in the vicinity of 5.9 eV which is larger by 0.7 eV than that expected from the onset of one-photon ionization. The ionization spectrum shows maxima at 5.92 and 5.99 eV which may be assigned to an autoionization process.
{"title":"Two-Color Two-Photon Ionization Spectrum of Pyrene in N-Hexane","authors":"K. Nakashima, Hirofumi Soga, T. Ogawa","doi":"10.1155/1997/83972","DOIUrl":"https://doi.org/10.1155/1997/83972","url":null,"abstract":"The photoionization process of pyrene in non-polar solvent has been investigated using a \u0000two-color two-photon ionization technique. The ionization spectrum near threshold of \u0000pyrene in n-hexane was measured by a delayed \u0000irradiation of a dye laser 20 ns after an N2 \u0000laser at total excitation energies of 5.9–6.22 eV. The two-photon ionization threshold of \u0000pyrene was in the vicinity of 5.9 eV which is larger by 0.7 eV than that expected from the \u0000onset of one-photon ionization. The ionization spectrum shows maxima at 5.92 and 5.99 \u0000eV which may be assigned to an autoionization process.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126359949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Single photon laser induced fluorescence (LIF) has been used to study the NO fragment produced in its ground electronic state from the 355 nm photolysis of CH3ONO. Populations of rotational, vibrational, spin-orbit and lambda doublet components have been measured. The results are in broad agreement with previous two photon LIF studies, and confirm the dynamics of the process in which the NO fragment departs from an essentially planar CONO framework with non-statistical energy partitioning in the internal states of the products.
{"title":"The 355 nm Photolysis of Methyl Nitrite","authors":"C. G. Atkins, G. Hancock","doi":"10.1155/LC.9.195","DOIUrl":"https://doi.org/10.1155/LC.9.195","url":null,"abstract":"Single photon laser induced fluorescence (LIF) has been used to study the NO fragment \u0000produced in its ground electronic state from the 355 nm photolysis of CH3ONO. \u0000Populations of rotational, vibrational, spin-orbit and lambda doublet components have \u0000been measured. The results are in broad agreement with previous two photon LIF \u0000studies, and confirm the dynamics of the process in which the NO fragment departs from \u0000an essentially planar CONO framework with non-statistical energy partitioning in the \u0000internal states of the products.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128154706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Nakajima, F. Ono, Y. Kihara, A. Ogawa, K. Matsubara, K. Ishikawa, M. Baba, K. Kaya
The geometric structures of 7-azaindole (7-AzI) and its dimer were investigated by laser-induced fluorescence (LIF). The rotationally resolved LIF spectrum (resolution: ∼0.00003 cm-1 of 7-AzI monomer shows that (i) rotational constants are A′′ 0.13082(5), B′′ = 0.05677(2), C′′ = 0.03970(1), A′ = 0.12468(5), B′ = 0.056752(2), and C′ = 0.03911(1), and (ii) the transition dipole moment direction is tilted at an angle of ± 21(5) degrees with respect to a axis. The LIF spectrum (resolution: ∼0.06 cm-1) of the nonreactive 7-AzI dimer suggests there are three possibilities for the geometric structure, having “single bonded”, “T-shaped”, and “non-planar” structures.
{"title":"Spectroscopic Study of Hydrogen Bonded7-Azaindole Clusters","authors":"A. Nakajima, F. Ono, Y. Kihara, A. Ogawa, K. Matsubara, K. Ishikawa, M. Baba, K. Kaya","doi":"10.1155/1995/63470","DOIUrl":"https://doi.org/10.1155/1995/63470","url":null,"abstract":"The geometric structures of 7-azaindole (7-AzI) and its dimer were investigated by laser-induced fluorescence (LIF). The rotationally resolved LIF spectrum (resolution: ∼0.00003 cm-1 of 7-AzI monomer shows that (i) rotational constants are A′′ 0.13082(5), B′′ = 0.05677(2), C′′ = 0.03970(1), A′ = 0.12468(5), B′ = 0.056752(2), and C′ = 0.03911(1), and (ii) the transition dipole moment direction is tilted at an angle of ± 21(5) degrees with respect to a axis. The LIF spectrum (resolution: ∼0.06 cm-1) of the nonreactive 7-AzI dimer suggests there are three possibilities for the geometric structure, having “single bonded”, “T-shaped”, and “non-planar” structures.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125449153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A picosecond absorption study on the intermolecular proton transfer of photoexcited 8-hydroxy-1,3,6-pyrene trisulfonate (HPTS) is presented. The time of formation of deprotonated excited HPTS was measured for various solvents. The dependence of this time of formation on the methanol fraction in watermethanol mixtures is discussed in terms of a simple cluster model. Proton transfer rates were determined in different micellar systems yielding information on the character of the micellar surrounding of the proton donator.
{"title":"Investigation of Solvent Dependence of Intermolecular Proton Transfer by Picosecond Absorption Spectroscopy","authors":"M. Kaschke, A. Granesz, J. Kleinschmidt","doi":"10.1155/LC.7.41","DOIUrl":"https://doi.org/10.1155/LC.7.41","url":null,"abstract":"A picosecond absorption study on the \u0000intermolecular proton transfer of photoexcited \u00008-hydroxy-1,3,6-pyrene trisulfonate (HPTS) \u0000is presented. The time of formation of deprotonated \u0000excited HPTS was measured for various \u0000solvents. The dependence of this time of \u0000formation on the methanol fraction in watermethanol \u0000mixtures is discussed in terms of a \u0000simple cluster model. Proton transfer rates \u0000were determined in different micellar systems \u0000yielding information on the character of the \u0000micellar surrounding of the proton donator.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121759089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In a flow reactor a low power (up to 50 W) CW CO2 laser tuned at 944,19 cm−1 has been focussed in order to produce Si and Si3N4 ultrafine powders from SiH4 and SiH4/NH3 mixtures.
{"title":"CARS DIAGNOSTIC ON A PHOTOCHEMICAL REACTOR FOR IR LASER INDUCED PRODUCTION OF Si AND Si3N4 POWDERS","authors":"R. Fantoni, F. Bijnen, N. Djurić, S. Piccirillo","doi":"10.1155/LC.11.13","DOIUrl":"https://doi.org/10.1155/LC.11.13","url":null,"abstract":"In a flow reactor a low power (up to 50 W) CW CO2 laser tuned at 944,19 cm−1 has been focussed in order \u0000to produce Si and Si3N4 ultrafine powders from SiH4 and SiH4/NH3 mixtures.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132325472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An investigation is presented of the transient vibrational excitation of O3 in the collision dominated regime initiated by pulsed CO2-laser radiation. IR-UV-double resonance experiments and measurements of the absorbance for the CO2-laser lines 9P18, 20, and 22 were carried out. Mixtures of O3 (p=17 mbar) with 02 were investigated at pressures of 160 mbar ≤Pmixt≤1200 mbar and laser fluences of 0.10 J/cm2≤Fin< 2 J/cm2 . The results are interpreted by numerical simulations in terms of a comprehensive excitation/relaxation model based upon SSH-theory. Concerning the evolution of the excitation, simulated transients of the UV-absorbance compare well with the corresponding observed signals. The saturation of the absorbing O3-transitions is demonstrated by the measured fluence dependence of the absorption coefficient at the laser wavelengths. The extent of the 03-excitation can be deduced according to the model from the maximum vibrational temperature Tm reached in the v1- and v3-oscillators. Tm accessible via the UV-transients and also via the absorbed laser energy in the case of slow relaxation at 160 160mbar≤Pmixt≤340 mbar. In this range both techniques result in the same values for Tm. The experimental and the corresponding simulated Tm depend exponentially on the laser fluence (Tm =const . F¯in0.3) provided Tm>400K being also confirmed up to Pmixt=1200 mbar by the observed UV-transients.
{"title":"Pulsed Co2-Laser Excitation of 03/02 Mixtures at Pressures From 0.16 to 1.20 Bar","authors":"B. Raffel, J. Wolfrum","doi":"10.1155/1990/93626","DOIUrl":"https://doi.org/10.1155/1990/93626","url":null,"abstract":"An investigation is presented of the transient vibrational excitation of O3 in the collision dominated \u0000regime initiated by pulsed CO2-laser radiation. IR-UV-double resonance experiments and measurements \u0000of the absorbance for the CO2-laser lines 9P18, 20, and 22 were carried out. Mixtures of O3 (p=17 mbar) \u0000with 02 were investigated at pressures of 160 mbar ≤Pmixt≤1200 mbar and laser fluences of 0.10 J/cm2≤Fin< 2 J/cm2 \u0000. The results are interpreted by numerical simulations in terms of a comprehensive \u0000excitation/relaxation model based upon SSH-theory. Concerning the evolution of the excitation, simulated \u0000transients of the UV-absorbance compare well with the corresponding observed signals. The \u0000saturation of the absorbing O3-transitions is demonstrated by the measured fluence dependence of the \u0000absorption coefficient at the laser wavelengths. The extent of the 03-excitation can be deduced according \u0000to the model from the maximum vibrational temperature Tm reached in the v1- and v3-oscillators. Tm \u0000accessible via the UV-transients and also via the absorbed laser energy in the case of slow relaxation at 160 \u0000160mbar≤Pmixt≤340 mbar. In this range both techniques result in the same values for Tm. The experimental \u0000and the corresponding simulated Tm depend exponentially on the laser fluence (Tm =const . F¯in0.3) \u0000provided Tm>400K being also confirmed up to Pmixt=1200 mbar by the observed UV-transients.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130014826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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