High harmonic generation from multiple orbitals in N2.
Molecular electronic states energetically below the highest occupied molecular orbital (HOMO) should contribute to laser-driven high harmonic generation (HHG), but this behavior has not been observed previously. Our measurements of the HHG spectrum of N2 molecules aligned perpendicular to the laser polarization showed a maximum at the rotational half-revival. This feature indicates the influence of electrons occupying the orbital just below the N2 HOMO, referred to as the HOMO-1. Such observations of lower-lying orbitals are essential to understanding subfemtosecond/subangstrom electronic motion in laser-excited molecules.
McFarland
Brian K
BK
PULSE Institute, SLAC, Menlo Park, CA 94025, USA, and Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA.
Farrell
Joseph P
JP
Bucksbaum
Philip H
PH
Gühr
Markus
M