Double Resonance REMPI of Formaldehyde ³A₂(n,3p_x) and ¹A₂(n,3p_x) Rydberg States

The Rydberg states ³A₂(n,3p_x) and ¹A₂(n, 3p_x) of formaldehyde were studied by using (1+2+1) OODR REMPI:ions←^1,3A₂(n,3p_x)←←Ã or ã←\tildeX. This is the first experimental observation of the formaldehyde ³A₂(n, 3p_x) state. The vibrational structure and partially resolved rotational structure of these two states have been obtained via selected vibration-rotational levels of Ã^-1A₂ state and ã³A₂ state respectively as an intermediate resonance level. The origins of ¹A₂(n, 3p_x) state and ³A₂(n,3p_x) state are at 67809cm^-1 and at 67400cm^-1 respectively. Both states are nonplanar geometry. A preliminary assignment for ³A₂(n,3p_x) 4² band rotational structure was given with the approximate rotational constants A=9.40 cm^-1 and B=0.96cm¹.