VIBRONIC ANALYSIS OF FLUORESCENCE SPECTRUM OF NO2 (D)OVER-TILDE(2)B(2)(0,0,0) IN THE REGION OF 250-550 NM

摘要

The dispersed fluorescence spectrum of NO2 (D) over tilde(2)B(2)(0,0,0) was measured and analyzed in the spectral range of 250-550 nm. The strong fluorescence bands in 250-350 nm correspond to (D) over tilde(2)B(2)(0,0,0)-->(X) over tilde(2)A(1)(n(1)=0-9, n(2)=0-5, n(3)=0) with a Franck-Condon maximum at n(1)=4 and n(2)=0. The weak and broad bands in 350-410 nm are built on a progression of bending frequency, 710 cm(-1). The lower state responsible for this fluorescence was interpreted as admixture B-ev(2) levels generated by a vibronic coupling between a(1)-vibrational levels on (A) over tilde(2)B(2) and highly excited b(2) (X) over tilde(2)A(1). The medium-intensity bands in 410-550 nm were assigned to (D) over tilde(2)B(2)(0,0,0)-->(C) over tilde(2)A(2)(n(1)=0-2, n(2)=0-5, n(3)=0-2) with a Franck-Condon maximum at n(1)=0, n(2)=2, and n(3)=0. The vibrational frequencies of (C) over tilde(2)A(2) are 1010 cm(-1) for symmetric stretch (omega(1)), 740 cm(-1) for bending (omega(2)), and 250 cm(-1) for antisymmetric stretch (omega(3)). The simple Franck-Condon calculation for (D) over tilde(2)B(2)(0,0,0)-->(C) over tilde(2)A(2)(n(1),n(2),n(3)) gives the approximate geometry of the (C) over tilde(2)A(2) State as r(N-O)similar to 134 pm and theta similar to 108 degrees. The partial rotational structure of (C) over tilde(2)A(2)(0,0,0) was analyzed using an optical-optical double resonance measurement, which confirms the A(2) vibronic symmetry. The origin of NO2 (C) over tilde(2)A(2) (T-0) was determined to be around 16 234 cm(-1). (C) 1996 American Institute of Physics. [References: 22]