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1.
The present analysis substantially improves the spectroscopic characterization of near infrared OCS in a window region (3850-4200 cm−1) important for atmospheric studies of Venus. Previous studies in this spectral region cataloged numerous OCS line positions, but accurate line intensities were measured for only three strong bands. In this paper, the corresponding line intensities are obtained for 41 OCS bands, including weak isotopic bands reported for the first time. The 2ν3 (0002-0000) band is analyzed for 10 OCS isotopologues (adding 16O13C34S, 17O12C32S, 16O12C36S, 18O12C34S, and 16O13C33S). In addition, observations of 0332-0330 of the main isotope, 16O12C32S, provides accurate vibration-rotation parameters for the upper state (and the lower state, 0330 of 16O12C32S). Finally, one unidentified band is seen at 3969.3 cm−1; its lower state is clearly the ground state of 16O12C32S. The line strengths of these seven previously unanalyzed bands plus 34 other bands of the OCS isotopologues, 16O12C32S, 16O12C34S, 16O13C32S, 16O12C33S, and 18O12C32S, were least-squares fitted to determine strength parameters, Sv and Herman-Wallis coefficients. Finally, the intensities of 17 additional very weak bands were estimated to provide an extensive new database of OCS line parameters to support remote sensing of Venus. The integrated intensity in cm−1/(molecule cm−2) at 296 K is 8.1×10−19 for the 3800-4200 cm−1 region.  相似文献
2.
利用高里德堡态氢原子飞行时间 (HRTOF)探测技术 ,研究了正丙醇和异丙醇的紫外光解动力学过程 .在 193.3nm光辐射下 ,O -H键快速断裂过程构成主要的氢原子生成通道 .伴随O -H键的碎裂 ,相当大的一部分能量转换成氢原子及其相应碎片的平动能 (正丙醇〈fv〉 =0 .76 ;异丙醇〈fv〉 =0 .78) .氢原子碎片具有各向异性的角度分布 ;其角分布异向因子 β分别为 - 0 .79(正丙醇 )和 - 0 .77(异丙醇 ) .研究结果表明 ,吸收 1个 193.3nm光子后 ,丙醇分子跃迁到一个寿命很短的电子激发态 ;沿着O -H反应坐标 ,该激发态势能面是排斥的 ,因而O -H键快速断裂 .此外 ,还得到了丙醇的O -H键离解能 :(432± 2 )kJ/mol(正丙醇 )和 (433± 2 )kJ/mol(异丙醇 ) .  相似文献
3.
Multi-decade atmospheric OCS (carbonyl sulfide) infrared measurements have been analyzed with the goal of quantifying long-term changes and evaluating the consistency of the infrared atmospheric OCS remote-sensing measurement record. Solar-viewing grating spectrometer measurements recorded in April 1951 at the Jungfraujoch station (46.5°N latitude, 8.0°E longitude, 3.58 km altitude) show evidence for absorption by lines of the strong ν3 band of OCS at 2062 cm−1. The observation predates the earliest previously reported OCS atmosphere remote-sensing measurement by two decades. More recent infrared ground-based measurements of OCS have been obtained primarily with high-resolution solar-viewing Fourier transform spectrometers (FTSs). Long-term trends derived from this record span more than two decades and show OCS columns that have remained constant or have decreased slightly with time since the Mt. Pinatubo eruption, though retrievals assuming different versions of public spectroscopic databases have been impacted by OCS ν3 band line intensity differences of ∼10%. The lower stratospheric OCS trend has been inferred assuming spectroscopic parameters from the high-resolution transmission (HITRAN) 2004 database. Volume mixing ratio (VMR) profiles measured near 30°N latitude with high-resolution solar-viewing FTSs operating in the solar occultation mode over a 22 years time span were combined. Atmospheric Trace MOlecucle Spectroscopy (ATMOS) version 3 FTS measurements in 1985 and 1994 were used with Atmospheric Chemistry Experiment (ACE) measurements during 2004-2007. Trends were calculated by referencing the measured OCS VMRs to those of the long-lived constituent N2O to account for variations in the dynamic history of the sampled airmasses. Means and 1-sigma standard deviations of VMRs (in ppbv, or 10−9 per unit air volume) averaged over 30-100 hPa from measurements at 25-35°N latitude are 0.334±0.089 ppbv from 1985 (ATMOS Spacelab 3 measurements), 0.297±0.094 ppbv from 1994 ATLAS 3 measurements, 0.326±0.074 ppbv from ACE 2004 measurements, 0.305±0.096 ppbv from ACE 2005 measurements, 0.328±0.074 from ACE 2006 measurements, and 0.305±0.090 ppbv from ACE measurements through August 2007. Assuming these parameters, we conclude that there has been no statistically significant trend in lower stratospheric OCS over the measurement time span. We discuss past measurement sets, quantify the impact of changes in infrared spectroscopic parameters on atmospheric retrievals and trend measurements, and discuss OCS spectroscopic uncertainties of the current ν3 band parameters in public atmospheric databases.  相似文献
4.
A spectrometer operating in the 100-2000 GHz range and allowing for absolute line strength measurements has been developed. The continuous wave terahertz radiation is generated by mixing two Ti:Sapphire laser beams in a vertically integrated low temperature grown GaAs (LTG-GaAs) photomixer. Pure rotational lines of 16O12C32S in the ground vibrational state have been considered for J values up to 90. Observed self-broadening parameters are in agreement with those deduced from infrared experiments. For the first time in the submillimeter range, absolute line strengths have been determined, allowing for a determination of the electric dipole moment in good agreement with the value previously obtained from Stark effect measurements.  相似文献
5.
6.
建立了一套高分辨的离子速度影像装置。在这套装置中,离了透镜的设计是利用Simion7.0应用程序对电场中离子的空间分布进行模拟“聚焦”得到的,达到了将离了源空间分布中速度相同而位置不同的离子聚焦在同一点上的效果。利用这套装置研究了CCl3Br在267nm附近的光解反应产物Br(^2P3.2)和Br^*(^2P1.2)的速度和角度的分布,得到了β(Br)=-0.48,β(Br^*)=1.44。  相似文献
7.
8.
To support planetary studies of the Venus atmosphere, we measured line strengths of the 2v3, v1+2v2+v3, and 4v2+v3 bands of the primary isotopologue of carbonyl sulfide (16O12C32S), whose band centers are located at 4101.387, 3937.427, and 4141.212 cm−1, respectively. For this, infrared absorption spectra in normal carbonyl sulfide (OCS) sample gas were recorded at an unapodized resolution of 0.0033 cm−1 at ambient room temperatures using a Bruker Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory. The FTS instrumental line shape (ILS) function was investigated, which revealed no significant instrumental line broadening or distortions. Various custom-made short cells and a multi-pass White cell were employed to achieve optical densities sufficient to observe the strong 2v3 and the weaker bands in the region. Gas sample impurities and the isotopic abundances were determined from mass spectrum analysis. Line strengths were retrieved spectrum by spectrum using a non-linear curve fitting algorithm adopting a standard Voigt line profile, from which Herman–Wallis factors were derived for the three bands. The band strengths of 2v3, v1+2v2+v3, and 4v2+v3 of 16O12C32S (normalized at 100% of isotopologue) are observed to be 6.315(13)×10−19, 1.570(2)×10−20, and 7.949(20)×10−21 cm−1/molecule cm−2, respectively, at 296 K. These results are compared with earlier measurements and the HITRAN 2004 database.  相似文献
9.
    
Heterodyne frequency measurements have been made on the 12°0-00°0 band of carbonyl sulfide in the wavenumber range from 1866 to 1915 cm–1. Frequency measurement techniques reported earlier are used to measure the OCS absorption lines by means of a tunable diode laser, a CO laser local oscillator, and two CO2 lasers used as secondary frequency standards. A table of calculated absorption frequencies is given for OCS from 1866 to 1919 cm–1.  相似文献
10.
刘玉柱  肖韶荣  张成义  郑改革  陈云云 《物理学报》2012,61(19):193301-193301
大气臭氧层破坏越来越严重, 卤代烷烃在太阳紫外线辐射下解离生成破坏臭氧的游离态卤素原子, 是主要元凶之一. 本文选用碘甲烷作为校准分子, 利用离子速度成像技术和共振增强多光子电离技术测得碘甲烷在266 nm紫外光解离下产生的基态碘原子I(2P3/2)在不同聚焦电压下的离子速度影像, 得到离子速度成像系统的放大系数N=1.13. 并利用该系统研究了1, 4-氯溴丁烷在~ 234 nm紫外辐射下的解离动力学, 分析讨论了解离产生的基态Br (2P3/2)和激发态Br* (2P1/2)的速度和角度分布信息, 揭示了1, 4-氯溴丁烷在~ 234 nm紫外光解离产生基态Br原子和激发态Br* 原子的通道都是源于C-Br键排斥势能面上的快速解离. 文中通过计算碎片影像角度分布的各项异性参数β值, 得到了生成基态Br(2P3/2)和激发态Br* (2P1/2) 两个解离通道中的平行跃迁和垂直跃迁比例. 另外, 本文还对氯溴甲烷, 1, 2-氯溴乙烷, 1, 3-氯溴丙烷和1, 4-氯溴丁烷在~ 234 nm下的光解动力学进行比较, 分析得到双卤代烷烃分子解离机理对烷基支链长度的依赖关系.  相似文献
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