Study of hot bands in the B2Σ+u-X2Σ+g system of C-2 anion

Optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy was employed to observe the visible absorption spectra of the B^2Σ^+_u-X^2Σ^+_g electronic transition of C^-_2. Four hot bands (0,1), (1,2), (2,3) and (3,4) have been observed and the band (3,4) is measured directly for the first time, so far as we know, by absorption. A rotational analysis was carried out to obtain molecular constants. With the Franck－Condon principle and the vibrational Boltzmann distribution, we have estimated the vibrational temperature of C^-_2 to be about 3000K.     

Rotational analysis of the c3Πu–b3Πg system of P2

The rotationally resolved spectra of the c³Π_u–b³Π_g system of P₂ in the 16620–17860 cm^?1 region is reanalyzed here to obtain more assignments of the rotational lines and more accurate molecular constants. Approximately 500 spectral lines were assigned to six subbands: the Ω=0, 1 and 2 components of the (2, 3) band, the Ω=0 and 2 components of the (1, 3) band and the Ω=2 component of the (1, 2) band. Because of perturbations in the c³Π_u (υ=2) state, the Λ-doubling in the ³Π₂–³Π₂ subband of the (2, 3) band was resolved. By the weighted nonlinear least-squares fitting using two types of effective Hamiltonians, more accurate molecular constants for the υ′=1 and 2 levels in the c³Π_u state and for the υ″=2 and 3 levels in the b³Π_g state of P₂ were derived.     

光外差-磁旋转-浓度调制光谱技术

介绍了一种针对瞬态分子光谱测量的新技术:光外差磁旋转浓度调制光谱技术,这种光谱技术具有很高的灵敏度,综合了光外差探测技术、磁旋转光谱技术和浓度调制光谱技术的特点,利用浓度调制光谱技术针对寿命很短的瞬态分子和激发态分子的光谱进行测量,利用光外差探测技术可以消除来自光源的幅度涨落噪声,实现散粒噪声的测量极限,利用磁旋转光谱技术可以对顺磁性分子进行选择性的测量,并且进一步提高探测灵敏度。详细讨论了这种光谱技术的工作原理,并用这种技术对O2分子的b1Σg+-X3Σg-三重禁戒跃迁光谱进行测量,获得了很好的测量信噪比。并对该技术的灵敏度作了详细的分析,估计最小相对吸收度可达1.9×10-9以及O2分子三重禁戒跃迁的吸收截面为σ=2.4×10-24cm2。     

CO三重带系d3Δ-a3Π(4,0)和(5,0)带激光光谱研究

光外差磁旋转浓度调制激光光谱技术属于一种高灵敏度的吸收光谱测量方法 ,可以用于瞬态分子和激发态分子光谱的检测。采用这种技术分别在 16 4 0 0～ 16 6 5 0cm-1和 174 5 0～ 1775 0cm-1波段内直接观测到CO三重带系d3 Δ←a3 Π(4,0 ) (5 ,0 )振转吸收光谱。这种跃迁的上态d3 Δ1(v =4 ) ,d3 Δ2 (v =4 ) ,d3 Δ1(v =5 )分别与A1Π(v =0 ) ,D1Δ(v =0 )和A1Π(v =1)态存在微扰相互作用。通过对所测量到的 CO三重带系 (4,0 ) (5 ,0 )振转谱带作了包含微扰相互作用在内的分析 ,获得了上态d3 Δ(v =4 ,5 )的精确的分子转动光谱常数。     

Analysis of （1, 2） （1, 3） and （2, 3） Bands in the c^3Ⅱu- b^3Ⅱg System of P2

We investigate the high resolution absorption spectroscopy of P2 radical, generated in ac glow discharge of PC13 buffered with helium, using optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy in the visible region. The （1, 2）, （1, 3） and （2, 3） bands of c^3Ⅱu- b^3Ⅱg in the range 16620-17860cm^-1 are observed and their 3II2 3II2 subbands are rotationally analysed. A set of effective molecular constants for the Ω= 2 component of the states involved are determined.