The π, π* state in formaldehyde and thioformaldehyde

✍ Scribed by F. Grein; M. R. J. Hachey

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 858 KB
• Volume: 60
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1996)60:7<1661::aid-qua48>3.0.co;2-1

✦ Synopsis

For formaldehyde, the C -0 stretch potential of '(T, r*) crosses all 'A, Rydberg \r, r* + 2 system to these Rydberg states. For thioformaldehyde, the situation is similar but a shift in the potentials allows for direct observation of '(r, T * ) . In its ' ( T , T * ) state, H,CO is planar, having a low barrier of about 0.2 eV toward the nonplanar '(v, T * > state. For H,CS, the planar conformation of ' ( T , r*) is a saddle point, with '(v, r*) being the global minimum on the 2'A' surface. The triplet r, r* states of H,CO and H,CS are nonplanar, having inversion barriers of 0.1 and 0.05 eV, respectively. For both H,CO and H,CS, the T , r* configuration also crosses the ground-state configuration, which explains predissociation and radiationless transitions of some Rydberg states. otentials, such as n, 3p,, n, 3d,,, etc., thereby transferring the intensity of the unassigned