LOCALIZED ROTATIONAL PERTURBATION BETWEEN 5P-PI-D'' (UPSILON=2) AND 7P-PI (UPSILON=1) STATES OF H2

An unusual quantum defect has been found associated with the 5ppiD'' s tate of the nppi (2, 0) Rydberg series. Expected and observed delta5 a re 0.086 and 0.079, respectively. The abnormal value is considered to be a localized perturbation with the perturbing state. 7ppi(v = 1). Pr eviously, no-one has observed Q(1) of 7ppi-X (1, 0) in absorption, but a photoionization peak was observed at the position of R(0) in B''-X( 4, 0); the upper level (J = 1) was located 3-4 cm-1 below the autoioni zation limit (H-2+, v = 0, N = 1). The position of the peak is interpr eted as arising from the perturbation between the 5ppiD''(v = 2) and 7 ppi(v = 1) states.