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Advances in Laser Science-I最新文献

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Laser‐induced breakdown of UF6 and its application to flow diagnostics 激光诱导UF6击穿及其在流体诊断中的应用
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35825
S. W. Allison, M. Cates, B. Noel
{"title":"Laser‐induced breakdown of UF6 and its application to flow diagnostics","authors":"S. W. Allison, M. Cates, B. Noel","doi":"10.1063/1.35825","DOIUrl":"https://doi.org/10.1063/1.35825","url":null,"abstract":"Breakdown of gaseous UF6 can be produced with relatively low fluence (approximately 106 W/cm2) near‐uv pulsed laser light. A broad spectrum is produced consisting of hundred of atomic (U1 and U11) lines. Following breakdown, particles are formed from the dissociation/ionization products and the sample volume remains ionized for a long time. This sample volume is elevated in temperature, and a shock wave is produced. Other pertinent details are presented. A schlieren technique is described for observing the motion, hence velocity, of the temperature defect and shock wave. Also given is a flow visualization method based on imaging a long‐lived emission component with a gated (≥10‐ns) image intensifier system. These and other methods are prospective ways to perform flow diagnostics in gas centrifuges.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131768862","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}
引用次数: 0
The mechanism for multiphoton ionization and fragmentation of CH3I CH3I的多光子电离和碎裂机理
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35894
J. Han, Y. Gua, S. Su, J. F. Chen, Y. Ji, S. H. Liu
{"title":"The mechanism for multiphoton ionization and fragmentation of CH3I","authors":"J. Han, Y. Gua, S. Su, J. F. Chen, Y. Ji, S. H. Liu","doi":"10.1063/1.35894","DOIUrl":"https://doi.org/10.1063/1.35894","url":null,"abstract":"The experimental MPI mass spectrum of CH3I at 308 nm has been reported. The dependence of the yields of I+ and CH3I+ ions on the sample pressure and laser pulse energy have been measured. The fragmentation mechanism for CH3I at 308 nm is suggested, which involves competition between two MPI‐fragmentation pathways.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132907281","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}
引用次数: 0
State‐specific collision dynamics of OH radicals and N atoms OH自由基与N原子的特定态碰撞动力学
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35955
R. Copeland, D. Crosley, J. Jeffries
{"title":"State‐specific collision dynamics of OH radicals and N atoms","authors":"R. Copeland, D. Crosley, J. Jeffries","doi":"10.1063/1.35955","DOIUrl":"https://doi.org/10.1063/1.35955","url":null,"abstract":"Open shell species, with a variety of spectroscopically accessible quantum states, offer opportunities for laser generation of nonequilibrium spatial distributions in both the laboratory (mJ) and molecular (Λ‐doublet) frames. In addition, laser excitation can also select the relative orientation of the spin and orbital angular momentum in these systems. The quantum state distributions can be interrogated by a delayed second laser pulse or by resolving the polarization and/or wavelength of the resulting fluorescence. In experiments on the OH radical, we have observed propensities for retention of electronic parity and spatial orientation during rotationally inelastic collisions of, respectively, the X 2Πi and A 2Σ+ electronic states. In nitrogen atoms, we have qualitatively determined the magnitude of fine structure, mJ and electronic state changing collisions in the 2s22p23p 4D0 electronic state.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133793035","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}
引用次数: 0
Resonance ionization mass spectrometry of Mg: The 3pnd autoionizing series 镁的共振电离质谱分析:3pnd自电离系列
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35704
R. Bonanno, C. Clark, J. D. Fassett, T. Lucatorto
{"title":"Resonance ionization mass spectrometry of Mg: The 3pnd autoionizing series","authors":"R. Bonanno, C. Clark, J. D. Fassett, T. Lucatorto","doi":"10.1063/1.35704","DOIUrl":"https://doi.org/10.1063/1.35704","url":null,"abstract":"We have utilized stepwise multiphoton excitation to observe autoionizing Rydberg states of magnesium. We observe the 3pnd series which converges to the 3 p 2P0 limits of the Mg ion. Our measurements extend up to n=40. A preliminary quantum defect analysis will be presented.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"313 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124442571","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}
引用次数: 0
Unimolecular reactions of isolated, collisional gas phase and solvated molecules: Connections between stilbene isomerization rates under supersonic jet and thermal gas phase conditions 分离、碰撞气相和溶剂化分子的单分子反应:超音速射流和热气相条件下二苯乙烯异构化速率之间的联系
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35907
M. W. Balk, S. H. Courtney, G. Fleming
{"title":"Unimolecular reactions of isolated, collisional gas phase and solvated molecules: Connections between stilbene isomerization rates under supersonic jet and thermal gas phase conditions","authors":"M. W. Balk, S. H. Courtney, G. Fleming","doi":"10.1063/1.35907","DOIUrl":"https://doi.org/10.1063/1.35907","url":null,"abstract":"Photochemical isomerization provides a practical testing ground for activated barrier crossing theories. Stilbene is a prototype, because (1) reaction may be initiated by a short optical pulse and the decay of the excited trans isomer followed optically, and (2) the isomerization rate is slow compared to vibrational or solvent relaxation processes in solution. The goal is to understand the effects of the medium upon the reaction kinetics proceeding from the isolated molecule to the low and the high pressure gas, and liquid solution. Towards this end time correlated single photon counting experiments of stilbene isomerization are discussed from isolated molecule conditions up to 90 atm of methane gas. In statistical theories of barrier crossing the transition state rate at temperature T, kTST(T), represents an upper limit for the reaction rate. However, contrary to expectation, for pressures greater than about 2 atm the isomerization rate was found to exceed kTST(T) by over a factor of 2 at 5 atm, and by a...","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114325666","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}
引用次数: 0
Electron acceleration in a laser‐irradiated plasma* 激光辐照等离子体中的电子加速*
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35874
Sang-Hoon Kim, K. W. Chen
{"title":"Electron acceleration in a laser‐irradiated plasma*","authors":"Sang-Hoon Kim, K. W. Chen","doi":"10.1063/1.35874","DOIUrl":"https://doi.org/10.1063/1.35874","url":null,"abstract":"Net inverse bremsstrahlung was previously found to give rise to a very large net dc force acting on relativistic electrons by a laser light in a longitudinal electrostatic plasma field. The predicted incident energy dependence of electron acceleration by co‐propagating laser waves and the weaker longitudinal electrostatic waves is in qualitative agreement with the preliminary results of a recent Canadian INRS‐Energie laser‐plasma electron acceleration experiment. The experimental results are not explained by acceleration mechanisms requiring phase matching such as that in the beat wave acceleration models.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"175 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115093309","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}
引用次数: 0
Laser‐enhanced spin‐exchange collisions 激光增强自旋交换碰撞
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35897
L. Vahala, M. Havey
{"title":"Laser‐enhanced spin‐exchange collisions","authors":"L. Vahala, M. Havey","doi":"10.1063/1.35897","DOIUrl":"https://doi.org/10.1063/1.35897","url":null,"abstract":"Spin‐exchange collisions between optically pumped alkali atoms and rare gas atoms can polarize the nuclei of rare gas atoms. We present calculations which indicate that the process should be readily modified by relatively weak (<1 KW/cm2) CW laser radiation tuned in the vicinity of the Rb‐rare gas 5sΣ−6sΣ free‐bound molecular transition. Full coupling of the spin‐polarized Rb electronic spin to the rare gas nuclear spin in the excited state lifetime leads to an estimate for Rb–Xe of a cross section σ≂10−22 Pcm2, where P is the laser power in KW/cm2.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"619 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116454292","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}
引用次数: 0
Femtosecond resolution ultrafast ion reaction time measurement a pulsed‐laser field desorption time‐of‐flight spectroscopy 飞秒分辨率超快离子反应时间测量-脉冲激光场解吸-飞行时间光谱
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35910
T. Tsong
{"title":"Femtosecond resolution ultrafast ion reaction time measurement a pulsed‐laser field desorption time‐of‐flight spectroscopy","authors":"T. Tsong","doi":"10.1063/1.35910","DOIUrl":"https://doi.org/10.1063/1.35910","url":null,"abstract":"Using a pulsed‐laser field desorption technique and an ion reaction time amplification scheme for the time‐of‐flight spectroscopy, dissociation by atomic tunneling of 4HeRh2+ in a field of ∼3 to 4.5 V/A has been measured to be 790±21 fs. This is the time for the ion to rotate 180°. A strong isotope effect by replacing 4He with 3He confirms the ion reaction to be produced by atomic tunneling of a mass dependent potential barrier.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122016126","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}
引用次数: 0
Activities at LINL relevant to gamma‐ray laser concepts 在LINL与伽马射线激光概念相关的活动
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35732
F. Dietrich
{"title":"Activities at LINL relevant to gamma‐ray laser concepts","authors":"F. Dietrich","doi":"10.1063/1.35732","DOIUrl":"https://doi.org/10.1063/1.35732","url":null,"abstract":"Current and planned gamma‐ray laser activities at Lawrence Livermore National Laboratory are discussed. The construction of a new accelerator laboratory that will include a facility for gamma‐ray laser candidate searches is also discussed.","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127057474","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}
引用次数: 0
Possible new lasers based on plasmas similar to thermionic converters 可能的新型激光器基于类似于热离子转换器的等离子体
Advances in Laser Science-I Pub Date : 2008-06-05 DOI: 10.1063/1.35879
E. Britt, J. Lawless, J. Mcvey
{"title":"Possible new lasers based on plasmas similar to thermionic converters","authors":"E. Britt, J. Lawless, J. Mcvey","doi":"10.1063/1.35879","DOIUrl":"https://doi.org/10.1063/1.35879","url":null,"abstract":"This paper describes novel plasma recombination lasers that can be produced with conditions similar to the plasma in a thermionic convertor. Calculations have shown that a population inversion can be obtained by either time variation of the current in a thermionic converter discharge or by gas dynamic expansion of plasma flow driven by heat pipe action. Sudden modulation of the current can cool the plasma in a thermionic convertor with electrons coming from the thermionically emitting electrode to produce an inversion of the 7p‐7s line in cesium. Alternatively, if the inter‐electrode plasma is made to flow through a supersonic expansion nozzle, a population inversion in the downstream plume may also be produced. Either of theses approaches or a combination of them can be used to convert heat directly into laser output. Two laser lines in the cesium vapor at 2.93 and 3.10 microns are predicted. Two other novel laser concepts are also mentioned: a solar pumped atmospheric laser and a laser based on the spac...","PeriodicalId":298672,"journal":{"name":"Advances in Laser Science-I","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127539574","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}
引用次数: 0
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