激光诱导NO2分子500-532nm区荧光激发谱的实验研究

用准分子激光抽运可调谐染料窄带激光测定了室温下NO2分子500-532nm区高分辨荧光激发谱,在两个较强吸收区505-510nm和513-520nm范围内标识了25个振动带,并作了转动分析,得到了相应的带头位置、转动常数和旋-转偶合常数等分子光谱常数,在25个振动带中有5个谱带是新发现的,所有得到转动分析的谱线均属于平行跃迁(X)2 A1-(A)2B2,对实验结果的分析表明电子激发态(A)2B2受到基态(X)2A1高振动能级的强烈扰动.     

Analysis of the LIF Spectroscopy of Nickel Hydride in 19000-21400 cm-1

采用放电溅射出的镍原子与甲醇气体在超声射流条件下产生NiH分子,获得了NiH分子在15000~21400 cm-1的激光诱导荧光激发谱．首次报道了NiH分子在19000~21400 cm-1的光谱．将观测到的24个谱带归属到7个不同的电子跃迁,并对每个谱带进行了转动分析．观测到了A、B、D、E、F和G态的高振动能级,得到了这些电子态的振动频率、非谐性常数、转动常数和平衡键长等较完整的光谱常数．并重新标识了一些谱带．     

激光诱导NO2分子500—532nm区荧光激发谱的实验研究

用准分子激光抽运可调谐染料窄带激光测定了室温下NO₂分子500—532nm区高分辨荧光激发谱,在两个较强吸收区505—510nm和513—520nm范围内标识了25个振动带,并作了转动分析,得到了相应的带头位置、转动常数和旋-转偶合常数等分子光谱常数,在25个振动带中有5个谱带是新发现的,所有得到转动分析的谱线均属于平行跃迁X～ ² A₁—A～²Ｂ₂,对实验结果的分析表明电子激发态A～ 关键词： 激光诱导荧光激发谱 振动带 转动分析     

高分辨高精密甲胺分子C—N伸缩带的兰姆凹陷饱和吸收红外光谱

甲胺分子(CH3NH2)是最简单的胺类分子,但由于分子中振动-转动-扭动-反转的相互作用使得其能级结构复杂和丰富密集且谱线强度差异很大的波谱,尤其是在频率中心位于1 044cm-1的C—N伸缩振动带。我们使用利用兰姆凹陷光谱技术自主研发的分辨率为0.4 MHz的二氧化碳激光和微波边带红外光谱仪将甲胺分子的C—N伸缩振动带的多普勒光谱中密集重合在一起的上百条谱线逐条分辨开和精密地测量了它们的跃迁频率。将它们标识归类和对J(J+1)作幂级数展开后,我们求得了27个系列的最初跃迁频率和它们的有效转动常数。     

射流冷却AlO自由基B2Σ+—X2Σ+光谱研究

利用铝电极放电产生的Al原子与O₂反应生成AlO自由基,在超声射流冷却下在43 0—480nm波长范围观测到AlO自由基B—X跃迁的激光诱导荧光激发谱.光谱振动结构分析表明 所有的谱带属于V′-V″=1,2,3跃迁,并获得基态和激发态的振动频率与非谐性常数.另外还 对其中(1,4)谱带的转动结构进行标识,并得到相应的转动常数和离心畸变系数.对从基态 振动能级V″=5向上跃迁的谱带强度增强进行了讨论. 关键词： 光谱 AlO     

Laser Induced Fluorescence Spectroscopy of IrN

利用激光蒸发/反应的自由射流膨胀和激光诱导荧光光谱方法,研究了IrN在394-520nm光谱区域的高分辨率激光诱导荧光光谱. 观察并分析了7个新的振动谱带. 确定了其中有两条是Ω=1和五条是Ω=0的新谱带. 用最小二乘法拟合了转动跃迁谱线,由此确定了高能级的精确光谱常数. 同位素分子光谱为振动光谱的标识提供了进一步的验证, 比较测得的IrB、IrC和IrN的电子态光谱推进了对这一系列分子的化学成键性质的认识.     

塞曼效应在Cl2+及其同位素分子离子

利用光外差磁旋转速度调制光谱技术获得了可见光波段(16820～17350cm-1)Cl2+分子离子的A2Πu-X2Πg电子跃迁吸收光谱.在标识Cl2+及其同位素分子离子谱带的过程中,应用塞曼效应,准确指认了属于Ω=1/2子带系的三个子带.它们分别是35Cl2+和35Cl37Cl+的(3,7)带的Ω=1/2子带以及35Cl2+的(2,7)带的Ω=1/2子带.其标识结果扩展了Cl2+分子离子的基态和激发态能级的振动标识范围,使各谱带的转动分析得以顺利进行,并获得了新的Cl2+分子常数.     

紫外光区S_2分子激光诱导荧光光谱

利用真空脉冲放电超声射流气体束(H_2S/Ar~3%混合气体)的方法产生了气相S_2分子,并研究了30 400~34 400cm~(-1)范围内S_2分子的时间分辨和基态振动频率分辨的激光诱导荧光光谱,获得了184支谱带的高分辨率(0.1cm~(-1))和低分辨率(0.3cm~(-1))转动光谱。实验观测并归属了S_2分子B_u~(Σ-)-X~3Σ_g~-和B″~3Π_u-X~3Σ_g~-共84支振动跃迁,分析得到了激发态B~3Σ_u~-态ν=0~9和B″~3Π_u态ν=2~12的分子常数以及B~3Σ_u~-态的基态平衡分子构型。由于S_2分子B~3Σ_u~-与B″~3Π_u态之间存在微扰,这两个电子激发态的振动能级间隔、自旋分裂常数和自旋-轨道分裂常数变化不规律,转动跃迁强度和跃迁选择定则存在异常,利用~3Σ-~3Π的齐次微扰哈密顿量定性地对这些异常光谱进行了解释,进一步丰富了S_2分子紫外区低能电子激发态的信息。     

双原子分子电子光谱的振动结构分析

从电子振转能级的光谱项出发,分析了双原子分子电子振动谱带序和电子振动谱带列的规律,并归纳出德兰德斯表(Deslandres table)及其主要性质。以C₂分子电子振动光谱的斯簧谱带系作为实例,说明了如何对电子振动光谱的测量值进行标识,并将它们按振动结构规律整理成德兰德斯表,从而获得有关分子光谱不同态的非谐性常数、振动频率等重要参数以及任意谱带的波数公式。     

Ar-D2O复合物在D2O弯曲振动模附近的新振转子带

稀有气体原子和水分子组成的范德瓦耳斯复合物是研究水和其他原子分子之间相互作用的典型模型.本文利用中红外连续外腔量子级联激光器结合脉冲超声分子束吸收光谱技术,在D₂O弯曲振动带(v₂=1←0)附近测量了Ar-D₂O复合物4个新的振动转动子带.基于赝双原子分子有效哈密顿量,本文对测量到的振动转动谱线和前人报道的下能级所涉及的纯转动谱线进行了最小二乘法全局拟合,得到了包括振动子能级能量、转动常数和离心畸变常数等在内的精确的基态和激发态分子参数.Ar-D₂O的D₂O弯曲振动激发的振动带头被精确确定为1177.92144 (32) cm^-1,该值比D₂O单体的带头红移了约0.458 cm^-1.将从实验得到的振动子能级能量与基于四维势能面的理论计算结果进行了比较,检验了理论计算方法的精度.     

S2O分子高激发振动光谱及势能面的代数研究

本文利用代数方法研究了非对称弯曲三原子分子S2O分子处于C～1A′电子态的能谱及其稳定构型下的势能面,通过对30条光谱数据的拟和得到的RMS误差为2.40 cm-1.结果表明,利用此代数Hamiltonian很好的实现了能级再现,它预测了振动总量子数达到20的全部振动能级(在本文中我们只列举到v= 9),同时我们计算了分子的解离能与力常数.通过与实验值比较证明了这种方法在计算这类分子的有效性.     

SF自由基的REMPI光谱：观测到一个新的2§电子态

利用SF6/Ar混合气沿气束方向放电， 产生SF自由基．在306?321 nm范围内扫描激光波长得到SF自由基(2+1) REMPI光谱． 观测到2§?X2|双光子跃迁的５ 个振转谱带， 通过对实验谱分析获得新观测到2§里德堡态的转动常数近似值和振动频率约815 cm?1；同时对2|3=2?X2|3=2跃迁谱带进行了转动分析，转动常数B0v?0.42 cm?1，该谱带对应着(1+2) REMPI机理；对SF自由基电离解离机理也进行了讨论．     

Pulsed Doppler-free two-photon spectroscopy of polyatomic molecules

Doppler-free two-photon electronic spectra of a large polyatomic molecule are recorded for the first time with pulsed laser radiation of near Fourier-transform limited bandwidth (Δv～100 MHz). The resolution obtained is sufficient to resolve individual rotational lines. Due to the high density of these rotational transitions a strong Doppler-broadened background is observed, which is, however, subtantially reduced by suitable choice of photon polarizations. Different vibronic bands of benzene (C₆H₆) are investigated and very accurate rotational constants are found.     

Identification of the SO2 cold vibronic bands in the 32 200–33 300 cm−1 region

Summary The fluorescence excitation spectrum of SO₂ in the 32 200–33 300 cm⁻¹ energy region was recorded, at very low rotational temperature, in a pulsed supersonic jet. The band centres and relative intensities of about 60 well-resolved vibronic bands were determined in this region, which extends the previously available data by 800 cm⁻¹. Single vibronic level fluorescence spectra of two neighbouring vibronic bands in theD-band region along with a few filtered excitation spectra are also presented as an example of the resolution for the listed bands. The authors of this paper have agreed to not receive the proofs for correction.     

Intracavity Laser Spectroscopy of NiCl System G: Identification of a [13.0] Π3/2 State

The (0,0) vibronic band of NiCl system G with a bandhead near 12 961 cm⁻¹ was recorded at high resolution in absorption using intracavity laser spectroscopy (ILS). For the ILS absorption spectra, the NiCl molecules were produced in a nickel hollow cathode, operated with a small amount of CCl₄, and line positions were referenced to iodine spectra. Fourier transform (FT) emission spectroscopy was used to record an extensive region of the spectrum used in a vibronic analysis of system G. For the FT spectra, excited NiCl molecules were produced in a high-temperature King-type carbon tube furnace. We show that this transition is the (0,0) vibronic band associated with a newly identified ²Π_3/2 excited state and the X²Π_3/2 ground state. The molecular constants for the new ²Π_3/2 electronic state are derived from the rotational analysis. Improved vibronic constants for the band are obtained from analysis of the FT spectra.     

The laser-induced fluorescence spectroscopy of gold monoxide: B2Σ−－X2Π3/2 transition

The electronic spectrum of the gaseous gold monoxide molecule has been investigated in the range of 16000－18500?cm^?1 using laser induced fluorescence spectroscopy and single vibronic level emission spectra. Five rotationally resolved vibronic bands are observed and assigned to the transitions B²Σ^? (v'?=?0－4) －X²п_3/2 (v''?=?0), in which the 0－0 transition is observed for the first time. The molecular constants of the excited state B²Σ^? are obtained by a rotational analysis of the spectra. The spin-orbit coupling constant and the vibrational constants of the ground state X²п_i are determined with the accuracy improved by one order of magnitude. The lifetimes of most observed bands are also measured for the first time.     

Doppler-limited dye laser excitation spectroscopy of DNO: Predissociation of DNO

The cw dye laser excitation spectrum of the (110)-(000) and (021)-(000) vibronic bands of the system of DNO was observed between 16530 and 16860 cm⁻¹ with Doppler-limited resolution. A rotational analysis of the two bands gave values for the rotational constants and centrifugal distortion constants. DNO was produced by the pyrolysis method and more than 1200 lines were observed in the two bands. A total of 1112 of these lines could be assigned to 9 and 11 subbands of the (110)-(000) and (021)-(000) bands, respectively. The molecular constants determined reproduce the observed transition frequencies with an average deviation of 0.011 and 0.008 cm⁻¹, respectively. Extensive perturbations in the excited state were found in most of the subbands. “Extra” lines were observed in connection with several of these perturbations. Accurate determination of the dissociation energy has been obtained; D₀ = 17010 ± 10 cm⁻¹.     

Vibronic Emission Spectrum of p-Xylyl Radical

We have obtained high-resolution Fourier transform emission spectra of the ? left and right arrow &Xtilde; transition of the jet-cooled p-xylyl radical in the 450-nm spectral region. The band contours of several vibronic bands are examined. By using the rotational constants obtained from previous high-resolution LIF spectra and information about the torsional constants from dispersed fluorescence experiments, both a-type and b-type band contours are simulated. Based on symmetry arguments and the results of the simulation, we have reassigned the 6a and 6b vibrational mode frequencies of the ground electronic state of the p-xylyl radical. Copyright 1999 Academic Press.