화학공학소재연구정보센터
Journal of Chemical Physics, Vol.106, No.15, 6231-6239, 1997
The Low-Lying Electronic States of CRF and Crcl - Analysis of the A(6)Sigma(+)-)X(6)Sigma(+) System of Crcl
A high-resolution near infrared spectrum of the CrCl radical has been recorded in thermal emission with Fourier transform techniques in the interval from 6 900 cm(-1) to 11 500 cm(-1). Two dominating band systems have been found in this region; (1) The A (6) Sigma(+) --> X (6) Sigma(+) system, analyzed in the present work, consisting of the (0,0), (0,1), (1,0), (2,0), and (3,0) bands, the (0,0) band being located at around 9450 cm(-1); (2) the B (II)-I-6-->X (6) Sigma(+) system, with a band interpreted as (0,0),located between 8700 cm(-1) and 9000 cm(-1), overlapping the (0,1) band of the A (6) Sigma --> X (6) Sigma(+) system. A rotational analysis of the A (6) Sigma(+) --> X (6) Sigma(+) system has been carried out, and the following principal parameters (cm(-1)) have been derived : X (6) Sigma(+) : omega(e) = 396.6621, B-e = 0.167 587 3, D-e = 1.1835 10(-7); A (6) Sigma(+) : omega(e) = 379.39, B-e = 0.156 51. Local perturbations in the A (6) Sigma(+) (v = 0,1) levels have been attributed to interactions with the B (II)-I-6 (v = 1,2) levels. In the present work, we have constrained the investigations on the B (II)-I-6 --> X (6) Sigma(+) system to the verification that the lower state is indeed X (6) Sigma(+). This verification has been achieved through successful matchings of branches in that system to known combination differences of X (6) Sigma(+). The assignment of the upper state as B (II)-I-6 is based on the characteristic appearance of the band. Ligand field and density functional calculations have been performed on CrF and CrCl. The results from these calculations indicate that the approximate structure of the B (II)-I-6 and 1 (6) Delta excited states of CrF and CrCl is Cr+[3d(4)4s(D-6)]X(-), while for the X (6) Sigma(+) ground state in both molecules it is Cr+[3d(4)4s(D-6) similar to 3d(5)(S-6)]X(-). A combined DFT/LFT treatment has been carried out on the Cr+ 3d(5) and 3d(4)4s configurations of both molecules in order to calculate the location of the A (6) Sigma(+) State and of a number of low-lying states in the quartet manifold.