15 research outputs found
Electric-Field-Induced Enhancement/Quenching of Photoluminescence of Ï-Conjugated Polymer S3-PPV: Excitation Energy Dependence
Rotationally Resolved Ultraviolet Spectroscopy of Indole, Indazole, and Benzimidazole - Inertial Axis Reorientation in the S-1((1)L(B))[-S-0 Transitions
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Rotational analysis of the origin and the inversion bands in the S1 (A2) ÂŹ S 0 (A1) electronic spectrum of acetaldehyde
Fully rotationally resolved spectra of the two lowest-frequency bands ~the origin (00 0 ) and the inversion (140 1) band! of the S1(n p*)ĂS0 transition of jet-cooled (Trot'6 K) acetaldehyde, CH3CHO, have been recorded with a resolution of '0.01 cm21 using a pulsed dye amplified continuous wave ~cw! laser. In modeling the spectra a nonperturbative solution of the rotationalâ torsional coupling problem was used, but the torsionâinversion and the rotationâinversion couplings were neglected. All the lines of the origin band were reproduced with a model using the same rotationalâtorsional Hamiltonian for the ground- and excited electronic state. The inversion band could not be described with this model, since the ordering of the torsional levels in the excited state is reversed. The measured spectrum was reproduced by using a rigid asymmetric rotor Hamiltonian for the two torsional levels in the excited state. Some rotational levels of 00 and 141 states were found to be shifted from their predicted energy values. These shifts were explained by an accidental resonance between the excited singlet level and some higher rovibronic triplet level. The relative intensities of the ab-type and c-type torsional subbands and the HerzbergâTellerâ induced transition dipole moment direction, characterizing the ab-type subband, were determined by an intensity fit