Revealing the Cooper minimum of N2 by molecular frame high-harmonic spectroscopy.
Molecular frame high-harmonic spectra of aligned N2 molecules reveal a Cooper-like minimum. By deconvolving the laboratory frame alignment distribution, what was previously thought to be a maximum of emission along the molecular axis is found to be maxima at 35 degrees off axis, with a spectral minimum on axis. Both of these features are supported by photoionization calculations that underline the relationship between high-harmonic spectroscopy and photoionization measurements. The calculations reveal that the on axis spectral minimum is a Cooper-like minimum that arises from the destructive interference of the p and f partial wave contributions to high-harmonic photorecombination. Features such as Cooper minima and shape resonances are ubiquitous in molecular photoionization or recombination.
Joint Attosecond Science Laboratory, National Research Council of Canada and University of Ottawa, 100 Sussex Drive, Ottawa, K1A 0R6, Canada.
J B
JB
Bertrand
H J
HJ
Wörner
P
P
Hockett
D M
DM
Villeneuve
P B
PB
Corkum