ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Optical–optical double-resonance excitation together with electron spectroscopy was used to measure the H+2 rotational state distributions produced by vibrational autoionization of singlet np Rydberg states of H2 . In the two-color excitation scheme, one laser was used to excite the two-photon transition to the H2 E, F 1∑+g, v'=1, J'=1 state, and a second laser was used to probe single-photon transitions to the vibrationally autoionized np Rydberg series converging to the X 2∑+g, v+=1, N¯+=1 and N¯+=3 levels of the ion. The expected P(1)npσ, Q(1)npπ, R(1)np1, and R(1)np3 Rydberg series converging to v+ =1 were observed and assigned, as were several interlopers converging to higher vibrational levels of the ion. Rotationally resolved photoelectron spectra were determined for all of the autoionizing transitions by using a magnetic bottle electron spectrometer. Under the normal assumptions that p waves are ejected and that spin effects are negligible, vibrational autoionization of the upper levels of the P(1)npσ and Q(1)npπ transitions should produce only v+ =0, N¯+ =1, while vibrational autoionization of the upper levels of the R(1)np1 and R(1)np3 transitions should produce a mixture of v+ =0, N¯+ =1 and v+ =0, N¯+ =3. Significant deviations from these expectations were observed. For example, vibrational autoionization of the upper levels of the Q(1)npπ transitions produced substantial amounts of v+ =0, N¯+ =3, while vibrational autoionization of the upper levels of certain Q(1)npπ, R(1)np1, and interloper transitions produced nonnegligible amounts of v+ =0, N¯+ =5. This indicates that vibrational autoionization of npπ Rydberg states is accompanied by rotational state changes in the H+2 core to an unexpected degree, and that additional mechanisms for exchange of angular momentum within the excited complex must be considered. Possible contributingmechanisms are critically assessed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.456341
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