Improvement in selectivity of isotope-selective ionization utilizing molecular alignment and angular dependent ionization

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

We are demostrating isotope-selective ionization of N and N isotopologues, utilizing molecular alignment and angular dependent ionization. In the present work, we used a train of four identical pulses with 125.7-ps interval to creating rotational wave packets in these isotopologues. We optimized the following experimental conditions to improve the isotope selectivity: mixing ratio of the gas sample, timing of pulse valve to introduce the gas sample into a vacuum chamber, laser beam diameters for the alignment and ionization pulses, and these peak intensities. As the results, we obtained the minimum of the ion yield ratio N/N (= 0.49) and the maximum (= 2.00).