丙酮团簇的多光子电离解离与结构计算

用355nm激光多光子电离解离飞行时间质谱观测到在超声分子束中形成的最多为12个分子的团簇离子及其碎片.用密度泛函方法对n=2～5的丙酮团簇结构进行计算,给出了优化构型及其基态能量.结果表明,两个丙酮分子组成团簇时稳定结构为近似垂直构型.3～5个丙酮分子组成团簇时以环状结构最稳定.     

XeCl准分子激光引发香芹酮的化学反应

本文报道了用XeCl准分子激光引发香芹酮(1)化学反应的研究结果.根据反应产物香芹酮樟脑(2)和1-挂,5-二甲基-顺2-[(乙氧羰基)甲基]双环[2.1.1]己烷(3)与激光照射能量的关系,得出香芹酮的1→2→3的反应过程.实验表明,在低激光强度照射时,每照射1焦耳能量生成2和3的量随着激光强度的增加而增加,并显示出饱和趋势.同时在照射过程中观察到浓度效应和发光.     

碘代烷烃在532 nm激光作用下多光子电离解离机理

利用５３２ｎｍ的激光对碘代烷烃（碘甲烷、碘乙烷、碘代正丙异丙烷）分子作了多光了电离解离（ＭＰＩＤ）质谱（ＭＳ）研究,在５３２ｎｍ激光作用下,ＣＨ３Ｉ分子吸收５３２ｎｍ激光双光子的能量,进入Ａ带的ＩＡ２态,继续吸收光子上泵浦至电离态形成母体离子ＣＨ３Ｉ,然后再形成碎片离子;而其它几个碘代烷烃吸收双光子的能量进入Ａ带后均形成中性碎片,中性碎片再吸收光子经一系列电离解离形成碎片离子,此外,本文还通过对同     

VA族元素氢化物的紫外光解和多光子电离 Ⅳ.SbH_3分子的紫外激光光解和多光子电离

用ArF激光(193nm)光解锑化氢,首次获得了在波长为403-700nm间的SbH_2发射光谱,其辐射寿命为70±20ns。还检测到了五十余条Sb(6s→5p)在紫外区的光谱谱线以及离子信号。它们都是多光子过程的产物。     

VA族元素氢化物的紫外光解和多光子电离 Ⅳ. SbH3分子的紫外激光光解和多光子电离

用ArF激光(193 nm)光解锑化氢, 首次获得了在波长为403-700 nm间的SbH_2发射光谱, 其辐射寿命为70±20 ns。还检测到了五十余条Sb(6s→5p)在紫外区的光谱谱线以及离子信号。它们都是多光子过程的产物。     

VA族元素氢化物的紫外光解和多光子电离Ⅲ. AsH3分子的紫外激光光解和多光子电离

通过193 nm的ArF激光光解AsH_3, 首次在420-650 nm之间观察到了AsH_2(Ã ~2A_1→X ~2B_1)的发射光谱。经过认证之后, 获得了v=19928+868v′_2-3v′_2~2-(989v″_2-6v″_2~2)的经验公式, 并辨认了七个谱带系。AsH_2(Ã ~2A_1)的辐射寿命是(130±20)ns。此外, 还观察到四条As(5s→4p)的原子发射谱线和多光子电离信号。     

一氧化碳的双共振多光子电离研究

用两束脉冲染料激光进行了CO的光学双共振四光子电离, 获得了转动分辩的CO A~(1Π)←X~(1Σ~+)和B~(1Σ~+)←A~(1Π)跃迁的光谱。观察到了在此2+1光子相继吸收中特有的选择定则。动力学研究表明CO基态到A~(1Π)态的双光子吸收是速率决定步骤, 其吸收截面约为1×10~(-49) cm~4 s。还测定了A~(1Π)态的单态转动传能截面。对于宇称指数e守恒、△J×±1的过程的截面约为0.05 nm; 随△J值增大而减小。对相同的△J, e正负变号的过程的截面总是小于e不变过程的截面。     

VA族元素氢化物的紫外光解和多光子电离——Ⅲ.AsH_3分子的紫外激光光解和多光子电离

通过193nm的ArF激光光解AsH_3,首次在420-650nm之间观察到了AsH_2(■2A_1→X 2B_1)的发射光谱。经过认证之后,获得了v=19928+868v′_2-3v′_2~2-(989v″_2-6v″_2~2)的经验公式,并辨认了七个谱带系。AsH_2(■2A_1)的辐射寿命是(130±20)ns。此外,还观察到四条As(5s→4p)的原子发射谱线和多光子电离信号。     

甲胺分子多光子电离质谱研究

胜多光子电离飞行时间质谱法，利用可调谐脉冲激光器，测得了甲胺分子在不同激光波长和激光功率下的多光子电离和解离产物。母体离子ＣＨ３ＮＨ＾＋２的离解速常数随激光发波长的增大而减小。     

甲硅烷的多光子电离

本文测量了SiH_4的(3+1)电离光谱。在激光波长428—458nm基本上是一个连续谱,在激光紫外区347—392nm,得到两个振动前进带组,并标识了一个位于363.5nm的谱带精细结构。用飞行时间质谱仪检测了碎片离子,没有观察到母体离子SiH_4~+,主要的产物离子是SiH_2~+和SiH_3~+,SiH_2~+和SiH_3~+离子产率的比值近似等于相同能量下的单光子电离结果,但Si~+的产率明显增加。在384—390nm范围的Si~+离子的光谱中比其它离子的光谱多出一些谱带,其增加的Si~+可能来自SiH_2~+和SiH~+离子的离解过程。     

PHOTOCHEMISTRY OF DNA USING 193 nm EXCIMER LASER RADIATION

Photoproducts in double-stranded DNA induced by 193 nm radiation have been investigated. Double-stranded, supercoiled pBR322 DNA in buffered aqueous solution was exposed to varying fluences of 193 nm radiation from an ArF excimer laser. The quantum yields for formation of cyclobutylpyrimidine dimers, frank strand breaks and alkali labile sites were calculated from the conversion of supercoiled (Form I) DNA to relaxed (Form II) DNA after treatment with Micrococcus luteus dimer-specific endonuclease, no treatment, or treatment with alkali and heat, respectively. The quantum yields were 1.65 (+/- 0.03) X 10(-3) for pyrimidine dimers, 9.4 (+/- 3.2) X 10(-5) for frank strand breaks and 9.6 (+/- 3.6) X 10(-5) for alkali labile sites. The quantum yields for pyrimidine dimers and strand breaks and alkali labile sites were not affected by 10 nM mannitol. The relative quantum yields for these DNA photoproducts induced by 193 nm radiation differed markedly from those produced by 254 nm radiation.     

四甲基硅的多光子电离光谱和质谱

在半导体生产中常用化学气相沉积(CVD)方法制备纯硅.所用的硅化合物原料中,四甲基硅是很重要的一种.与其它种类相比,它不象硅甲烷那样易爆,又不象卤代硅烷那样有腐蚀性,化学性质是比较稳定的.另一方面,它的分子结构Si(CH_3)_4与一般有机金属化合物类似,具有一定代表性.因此研究这个分子的离解和电离过程,以及光物理与光化学性质,在应用和学术方面都是有价值的。     

EFFECTS OF INTENSITY AND FLUENCE UPON DNA SINGLE-STRAND BREAKS INDUCED BY EXCIMER LASER RADIATION

Abstract— A Xenon-chloride excimer laser emitting energy at 308 nm was used to induce single-strand breaks (SSBs, frank breaks plus alkali-labile lesions as assayed by alkaline sucrose sedimentation techniques) in purified DNA from Bacillus subtilis . A fluence response study and a peak pulse intensity study were performed. At a pulse energy of 0.1 mJ/pulse, the radiation induced SSBs in a linear fashion (91 SSB/10⁸ Da per MJ/m²) to a maximum exprimental fluence of 1.28 MJ/m². The pulse intensity study showed that there were no significant changes in DNA breakage (105 SSB/10⁸ Da) between 2.93 times 10⁹ and 5.86 times 10¹¹ W/m² (0.11 and 22.0 mJ/pulse) at a constant total fluence of 1.1 MJ/m² (27000 mJ dose). This study has verified and extended previous work by quantifying the yield of SSBs induced in DNA by this laser radiation.     

MUTATION AND SISTER CHROMATID EXCHANGE INDUCTION IN CHINESE HAMSTER OVARY (CHO) CELLS BY PULSED EXCIMER LASER RADIATION AT 93 nm AND 308 nm AND CONTINUOUS UV RADIATION AT 254 nm

We compared mutagenesis and sister chromatid exchange (SCE) induction by 193 nm and 308 nm pulsed excimer laser radiation with 254 nm low intensity continuous wave UV light in Chinese hamster ovary (CHO) cells in culture. The 254 nm radiation was most mutagenic of the radiations, in accordance with expectation, and also was most effective in increasing the level of SCEs. The 193 nm radiation was mutagenic at the ouabain resistance locus, but not at the HGPRT locus. However, 193 nm radiation was also strongly cytotoxic at energies producing measurable mutations. This radiation also caused a dose-related increase in SCEs. Pulsed excimer radiation at 308 nm was mutagenic at both loci, and also increased the incidence of SCEs. Comparison of the ratio of mutants/surviving cells at the D37 after radiation showed similar values for 254 nm and 308 nm at the HGPRT locus, but at the ouabain resistance locus, the ratio for the 308 nm radiation was about 5 times that for 254 nm radiation. These results indicate that some risk for mutagenesis may accompany the use of excimer radiation in the UVA region in therapeutic applications.     

VA族元素氢化物的紫外光解和多光子电离Ⅰ. NH3分子紫外激光光解

在光强为10~6 W cm~(-2)的ArF激光作用下, NH_3分子被光解为NH(A~(3Π))先后吸收两个193 nm光予, 经过NH_3(Ã ~1A_2″)和NH_2( Ã ~2A_1)两个中间物的过程。NH(A~(3Π)→X~(3∑~-))的发射光谱表明, 该产物具有7700 K的转动高温。此系NH_2在激发过程中剧烈的变角效应所致。我们利用高功率的紫外激光器及时间分辩的测量仪器, 系统地研究了这些分子的光谱能级, 反应、光解机理和电离过程等, 显然有重要的意义。     

VA族元素氢化物的紫外光解和多光子电离Ⅱ. PH3的多光子电离光谱

用染料激光器在波长为300-640 nm范围内扫描, 观察到PH_3的一系列多光子电离光谱。其中351-398 nm的近二十条谱带, 其能级间隔约263 cm~(-1), 拟归属于通过Ã态的(2+1)电离谱。在460-495 nm的弱谱, 428-452 nm的六条谱带和385-398 nm之间的四条谱带, 则分别认证为相应于经历了B, C和D态的(3+1)MPI光谱。求得B态的项值T_0≤60729 cm~(-1), D态的T_0≤75567 cm~(-1), 而D态的反演振动频率ω_2为510 cm~(-1).     

ArF激光光致抗蚀剂的研究进展

本文对近10年来有关ArF激光(193nm)光致抗蚀剂的研究开发情况进行了调研,对193nm光致抗蚀剂组成物的各个组分进行了归纳综述.从本文可以看出,利用193nm成像技术可以刻画线幅很细(<0.13μm)的图像,能适应信息技术的发展对于光致抗蚀剂高分辨率的要求.但若想将193nm成像技术在实践中推广应用,还有诸多问题需待研究解决.