Selective ionization of oriented nonpolar molecules with asymmetric structure by phase-controlled two-color laser fields.

We report on the selective ionization of oriented nonpolar molecules with asymmetric structure by using phase-controlled two-color omega + 2omega laser pulses with an intensity of 1.0 x 10(13) W/cm(2) (tunneling ionization regime) and a pulse duration of 130 fs. The orientation of 1-bromo-2-chloroethane was monitored by the directional asymmetries of the forward-backward emission in dissociative ionization. The observed direction of orientation clearly confirms that molecular orientation is induced not by dynamic orientation but by selective ionization of oriented molecules, which reflects the structure of the highest occupied molecular orbital. This method can be applied for the vast majority of molecules.