Journal Article Isotope-selective ionization utilizing field-free alignment of isotopologues using a switched nanosecond laser pulse

赤木, 浩  ,  熊田, 高之  ,  Otobe, Tomohito  ,  Itakura, Ryuuji  ,  長谷川, 宗良  ,  大島, 康裕

124pp.14-1 - 14-8 , 2018-01 , Springer Berlin Heidelberg
We propose and numerically simulate a method of laser isotope separation based on field-free alignment of isotopologues, utilizing an intense “switched” nanosecond (ns) laser field which is slowly turned on and rapidly turned off at the peak with the falling time of 200 fs. The femtosecond (fs) laser induced alignment of molecules including a heavy atom is severely disturbed by ionization because of their small ionization potential. Our simulations for I79Br and I81Br isotopologues demonstrate that the switched ns laser field can make isotopologues well-aligned with the reduced ionization probability at the laser intensity [I0 = 2 TW/cm2 (= 2 × 1012 W/cm2)] which is an order-of-magnitude lower than a typical intensity (I0 = 20 TW/cm2) for field-free alignment induced by a fs laser field. In our simulations, IiBr isotopologues (i = 79 or 81) aligned with the switched ns laser field are selectively ionized by an intense fs laser pulse at an appropriate time delay from the alignment pulse.

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