Isotope-selective rotational excitation with a sequence of femto-second laser pulses

Akagi, Hiroshi; Kasajima, Tatsuya*; Kumada, Takayuki   ; Itakura, Ryuji; Yokoyama, Atsushi; Hasegawa, Hirokazu*; Oshima, Yasuhiro*

We propose a laser isotope separation utilizing difference of molecular rotational period, and experimentally demonstrate the principle, showing isotope selective ionization of N and N isotopologues. A linearly-polarized short laser pulse creates rotational wave packets in the isotopologues, which periodically revive with different revival times as a result of different moments of inertia. Another linearly-polarized short laser pulse ionizes one of the isotopologues preferentially, as a result of their different angular distributions and angular dependence of ionization probability. In the present experiment, the ion yield ratio R [= I(N)/I(N)] has been changed in the range from 0.85 to 1.22, depending on the time delay between the two laser pulses.