The action of pulsed high repetition rate UV laser radiation (2-nd harmonic of Cu vapor laser, λ = 271 nm, pulse duration 18 nsec, repetition rate 10 kHz) on proliferating and resting HeLa cells has been studied. The intensity of DNA synthesis changes after such kinds of irradiation for both types of cells. For proliferating cells DNA synthesis is suppressed, while for the resting ones stimulation is observed in the dose range from 0.05 to 5 J/m2.
{"title":"Different Responses of Proliferating and Resting Tumor HeLa Cells to Pulsed High Repetition Rate Low-Intensity Laser Light at 271 nm","authors":"T. Karu, G. Kalendo, V. Letokhov, V. Lobko","doi":"10.1155/LC.1.153","DOIUrl":"https://doi.org/10.1155/LC.1.153","url":null,"abstract":"The action of pulsed high repetition rate UV laser radiation (2-nd harmonic of Cu vapor \u0000laser, λ = 271 nm, pulse duration 18 nsec, repetition rate 10 kHz) on proliferating and \u0000resting HeLa cells has been studied. The intensity of DNA synthesis changes after such kinds \u0000of irradiation for both types of cells. For proliferating cells DNA synthesis is suppressed, \u0000while for the resting ones stimulation is observed in the dose range from 0.05 to 5 J/m2.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"36 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":"134271839","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}
When a protein finds its native three-dimensional structure from the unstructured amino-acid chain various processes spanning a large time range are relevant. To understand the mechanism of protein folding one needs to cover the entire folding/ refolding (U↔N) reaction on a structural level. In the case of RNase A, the main structural changes occur in the ms time range, that can be monitored with rapid-scan- FTIR spectroscopy combined with rapid mixing techniques. To induce unfolding we inject aqueous protein solution into a hot IR cuvette and record the time course of the spectral changes. A lag phase is found when the unfolding conditions are relatively weak, suggesting an unfolding intermediate.
{"title":"TEMPERATURE INDUCED PROTEIN UNFOLDING AND FOLDING OF RNase A STUDIED BY TIME-RESOLVED INFRARED SPECTROSCOPY","authors":"H. Georg, C. Wharton, F. Siebert","doi":"10.1155/1999/28202","DOIUrl":"https://doi.org/10.1155/1999/28202","url":null,"abstract":"When a protein finds its native three-dimensional structure from the unstructured amino-acid chain various processes spanning a large time range are relevant. To understand the mechanism of protein folding one needs to cover the entire folding/ refolding (U↔N) reaction on a structural level. In the case of RNase A, the main structural changes occur in the ms time range, that can be monitored with rapid-scan- FTIR spectroscopy combined with rapid mixing techniques. To induce unfolding we inject aqueous protein solution into a hot IR cuvette and record the time course of the spectral changes. A lag phase is found when the unfolding conditions are relatively weak, suggesting an unfolding intermediate.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"56 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":"134003576","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 temporal evolution of a plasma formed by the interaction of a Nd-YAG 10 ns laser pulse with the surface of aqueous solutions of CaCl 2 , has been observed by analyzing the variation of the emission spectra of ions and neutral atoms in the time interval after the laser pulse, 500 ns T e using a Saha-Boltzmann analysis. The broadening of the resonance line of CaI at 4227 A was used to deduce the electronic density N e , with the aid of the semiclassical theory of Stark broadening. A value of T e ≈ 28000 K decreasing slightly to 21000 K, and an exponential decay for N e were found, with N e ≈ 1:25 × 10 18 cm -3 at 500 ns and τ e = ( 1200 ± 50 ) ns.
利用Saha-Boltzmann分析方法，分析了Nd-YAG 10 ns激光脉冲与cacl2水溶液表面相互作用形成的等离子体在激光脉冲500 ns T后的时间间隔内离子和中性原子发射光谱的变化，观察了等离子体的时间演化。利用CaI在4227a处的共振线的加宽，借助Stark加宽的半经典理论，推导了电子密度ne。te≈28000 K略微下降至21000 K, ne呈指数衰减，在500 ns时，ne≈1:25 × 10 18 cm -3， τ e =(1200±50)ns。
{"title":"Temporal Characterization of a Plasma Produced by Interaction of Laser Pulses with Water Solutions","authors":"J. Ahmed, N. Terzi, Z. B. Lakhdar, G. Taieb","doi":"10.1080/02786270215155","DOIUrl":"https://doi.org/10.1080/02786270215155","url":null,"abstract":"The temporal evolution of a plasma formed by the interaction of a Nd-YAG 10 ns laser pulse with the surface of aqueous solutions of CaCl 2 , has been observed by analyzing the variation of the emission spectra of ions and neutral atoms in the time interval after the laser pulse, 500 ns T e using a Saha-Boltzmann analysis. The broadening of the resonance line of CaI at 4227 A was used to deduce the electronic density N e , with the aid of the semiclassical theory of Stark broadening. A value of T e ≈ 28000 K decreasing slightly to 21000 K, and an exponential decay for N e were found, with N e ≈ 1:25 × 10 18 cm -3 at 500 ns and τ e = ( 1200 ± 50 ) ns.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"73 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":"134341586","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}
Quantum beats in transient absorption of PIC-J-aggregates, modelled by a modified 3-level-system are calculated. Experimental conditions for the possibility of their observation are investigated. The influence of the temperature dependent phase relaxation on the temporal evolution of quantum beat signals is considered.
{"title":"Quantum Beats in Transient Spectroscopy of J-Aggregates","authors":"H. Glaeske, K. Feller, E. Gaiaukas, L. Knöll","doi":"10.1155/1996/63828","DOIUrl":"https://doi.org/10.1155/1996/63828","url":null,"abstract":"Quantum beats in transient absorption of PIC-J-aggregates, modelled by a modified 3-level-system are calculated. Experimental conditions for the possibility of their observation are investigated. The influence of the temperature dependent phase relaxation on the temporal evolution of quantum beat signals is considered.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"21 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":"132965008","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 Cs( 7 P)+H 2 → CsH + H reaction is studied in a crossed-beam experiment with laser-induced fluorescence detection of CsH products. The usual flux ( ≈ 50 mW / mm 2 ) which is delivered by the C.W. tunable dye laser used in the experiment is enough to saturate the absorption by CsH products. Then, by crossing twice the laser beam through the collision volume (counterpropagating beams), one realizes the conditions of saturated-absorption experiments: when the laser frequency is tuned to a resonance frequency of CsH products, a defect to absorption occurs for these products which scatter in the collision plane and a "saturation dip" appears at the center of the corresponding fluorescence profile. Application of this technique to crossed-beam experiments can lead to the selection of product molecules which scatter in any definite plane. A different geometry of the laser beams (bent beams) is proposed to select molecules which scatter in any definite direction: it could be applied to detect an asymmetry in the scattering of the products with respect to the collision axis, when a particular preparation of the reagents is realized.
{"title":"Angular selection of products by use of saturated-absorption techniques in the Cs(7P)+H2→CsH+H reaction","authors":"J. l’Hermite, G. Rahmat, R. Vetter","doi":"10.1155/1990/79301","DOIUrl":"https://doi.org/10.1155/1990/79301","url":null,"abstract":"The Cs( 7 P)+H 2 → CsH + H reaction is studied in a crossed-beam experiment with laser-induced \u0000fluorescence detection of CsH products. The usual flux ( ≈ 50 mW / mm 2 ) which is delivered by the C.W. \u0000tunable dye laser used in the experiment is enough to saturate the absorption by CsH products. Then, by \u0000crossing twice the laser beam through the collision volume (counterpropagating beams), one realizes the \u0000conditions of saturated-absorption experiments: when the laser frequency is tuned to a resonance \u0000frequency of CsH products, a defect to absorption occurs for these products which scatter in the collision \u0000plane and a \"saturation dip\" appears at the center of the corresponding fluorescence profile. Application \u0000of this technique to crossed-beam experiments can lead to the selection of product molecules which scatter \u0000in any definite plane. A different geometry of the laser beams (bent beams) is proposed to select molecules \u0000which scatter in any definite direction: it could be applied to detect an asymmetry in the scattering of the \u0000products with respect to the collision axis, when a particular preparation of the reagents is realized.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"153 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":"114626462","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}
J. Kauffman, C. Kelley, Alem Ghiorghis, E. Neister, Lorne Armstrong, Paul R. Prause
Partial bridging of the o,o′ positions of the aromatic rings in quaterphenyl gave superior flashlamp-pumpable laser dyes. Alkyl-substituted carbon bridges gave superior dyes to those containing oxygen or alkyl-substituted nitrogen or silicon bridges. Dyes lasing in the 365–390 nm region with improved energy output, lifetime and solubility were discovered.
{"title":"Bridged Quaterphenyls as Flashlamp-Pumpable Laser Dyes","authors":"J. Kauffman, C. Kelley, Alem Ghiorghis, E. Neister, Lorne Armstrong, Paul R. Prause","doi":"10.1155/LC.7.343","DOIUrl":"https://doi.org/10.1155/LC.7.343","url":null,"abstract":"Partial bridging of the o,o′ positions of the aromatic rings in quaterphenyl gave superior \u0000flashlamp-pumpable laser dyes. Alkyl-substituted carbon bridges gave superior dyes to \u0000those containing oxygen or alkyl-substituted nitrogen or silicon bridges. Dyes lasing in \u0000the 365–390 nm region with improved energy output, lifetime and solubility were \u0000discovered.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"151 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":"114907205","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}
With a state-selective laser excitation, two main decay processes, autoionization and predissociation, in vibrational superexcited Rydberg states (n = 8–12, l = s, p, and f, v = 1) of NO have been studied, directly detecting not only NO
在状态选择激光激发下，研究了NO在振动超激发Rydberg态(n = 8-12, l = s, p和f, v = 1)下的两个主要衰变过程，即自电离和预解离，直接探测的不仅仅是NO
{"title":"Laser Spectroscopic Investigation of High Rydberg States of no:Decay Dynamics Near the First Ionization Threshold","authors":"A. Fujii, N. Morita","doi":"10.1155/1994/49739","DOIUrl":"https://doi.org/10.1155/1994/49739","url":null,"abstract":"With a state-selective laser excitation, two main decay processes, autoionization and predissociation, in vibrational superexcited Rydberg states (n = 8–12, l = s, p, and f, v = 1) of NO have been studied, directly detecting not only NO","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"38 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":"114951896","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 double proton transfer of 2,2'-bipyridyl-3,3'-diol (BP(OH)2) in isooctane after UV excitation has been studied by excite and probe beam spectroscopy with a time resolution of 5 ps. Estimates for the excited state proton transfer rate as well as for the extinction coefficients of the excited state absorption bands of the primarily excited species and of the tautomer have been determined.
{"title":"Picosecond Studies of Intramolecular Double Proton Transfer by Excite- and Probe-Technique","authors":"M. Kaschke, S. Rentsch, J. Opfermann","doi":"10.1155/LC.8.377","DOIUrl":"https://doi.org/10.1155/LC.8.377","url":null,"abstract":"The double proton transfer of 2,2'-bipyridyl-3,3'-diol (BP(OH)2) in isooctane after UV excitation has been studied by excite and probe beam spectroscopy with a time resolution of 5 ps. Estimates for the excited state proton transfer rate as well as for the extinction coefficients of the excited state absorption bands of the primarily excited species and of the tautomer have been determined.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"169 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":"115044427","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}
This paper provides an overview of the method of single photon ionisation mass spectrometry. A review of the theory of frequency upconversion using third-order 4- wave sum mixing in isotropic media and experimental results of third harmonic generation (THG) using a frequency tripled 355 nm Nd:YAG pump source are presented. Vacuum Ultra-violet (VUV) photons of wavelength 118 nm are detected in an acetone ionisation chamber. The emphasis of this paper is on the practical aspects of generating and detecting the VUV photons and using them for single photon ionisation (SPI) in the ion source of a mass spectrometer. Optimum gas pressures for THG in Xe and Xe/Ar mixtures are established. For a pump beam of well defined mode structure the optimum gas pressures are in excellent agreement with theory. The major loss mechanism is attributed to re-absorption of VUV by the tripling gas. SPI mass spectra of hexane and the biomolecule valyl-valine are presented illustrating the power of the technique.
{"title":"SINGLE PHOTON IONISATION MASS SPECTROMETRY USING LASER-GENERATED VACUUM ULTRAVIOLET PHOTONS","authors":"N. Lockyer, J. Vickerman","doi":"10.1155/1997/53174","DOIUrl":"https://doi.org/10.1155/1997/53174","url":null,"abstract":"This paper provides an overview of the method of single photon ionisation mass \u0000spectrometry. A review of the theory of frequency upconversion using third-order 4- \u0000wave sum mixing in isotropic media and experimental results of third harmonic \u0000generation (THG) using a frequency tripled 355 nm Nd:YAG pump source are \u0000presented. Vacuum Ultra-violet (VUV) photons of wavelength 118 nm are detected in an \u0000acetone ionisation chamber. The emphasis of this paper is on the practical aspects of \u0000generating and detecting the VUV photons and using them for single photon ionisation \u0000(SPI) in the ion source of a mass spectrometer. Optimum gas pressures for THG in Xe \u0000and Xe/Ar mixtures are established. For a pump beam of well defined mode structure the \u0000optimum gas pressures are in excellent agreement with theory. The major loss \u0000mechanism is attributed to re-absorption of VUV by the tripling gas. SPI mass spectra \u0000of hexane and the biomolecule valyl-valine are presented illustrating the power of the \u0000technique.","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"66 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":"116018552","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}
T. Fournier, G. Scholes, I. Gould, S. Tavender, D. Phillips, A. Parker
A time resolved resonance Raman (TR3) study of 1-nitronaphthalene (1NN) first triplet excited state in various solvents is combined with ab initio calculations to determine the nature and the geometry of this state in environments of different polarity. A transient absorption and TR3 study of the reactions of triplet 1NN with trans-stilbene (tS) in solution in both non-polar and polar solvents is reported. In polar solution, 31NN acts as an electron acceptor whereas in non-polar solution only energy transfer to tS is observed. Moreover, at high concentrations of tS, the radical cation tS
{"title":"Triplet 1-nitronaphthalene and competitive energy and electron transfer reactions with trans-stilbene","authors":"T. Fournier, G. Scholes, I. Gould, S. Tavender, D. Phillips, A. Parker","doi":"10.1155/1999/92415","DOIUrl":"https://doi.org/10.1155/1999/92415","url":null,"abstract":"A time resolved resonance Raman (TR3) study of 1-nitronaphthalene (1NN) first triplet excited state in various solvents is combined with ab initio calculations to determine the nature and the geometry of this state in environments of different polarity. A transient absorption and TR3 study of the reactions of triplet 1NN with trans-stilbene (tS) in solution in both non-polar and polar solvents is reported. In polar solution, 31NN acts as an electron acceptor whereas in non-polar solution only energy transfer to tS is observed. Moreover, at high concentrations of tS, the radical cation tS","PeriodicalId":296295,"journal":{"name":"Laser Chemistry","volume":"36 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":"116353672","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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