The 1A2 ( n, 3 px) Rydberg state of formaldehyde

Abstract

Pairs of bands were observed in the absorption spectrum of H 2CO, HDCO, and D 2CO in the 1470-1430 Å region which were characterized by well-defined rotational band contours. A band contour synthesis of the observed band envelopes demonstrated that the bands are described by type C selection rules. From the observed intervals and their shifts on deuterium isotope substitution these bands were assigned to quantum additions of ν 5 and ν 6. The symmetry of the upper state was deduced to be 1 A 2 from the vibrational assignment of the bands and their polarizations, while the results from MO theory lead to the orbital assignment n → 3 p x . The electronic transition then is 1A 2 (n, 3p x) ← X ̃ , 1A 1 .