Femtosecond Rotational Dynamics of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">D</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> Molecules in Superfluid Helium Nanodroplets
Junjie Qiang, Lianrong Zhou, Peifen Lu, Kang Lin, Yongzhe Ma, Shengzhe Pan, Chenxu Lu, Wenyu Jiang, Fenghao Sun, Wenbin Zhang, Hui Li, Xiaochun Gong, Ilya Sh. Averbukh, Yehiam Prior, Constant A. Schouder, Henrik Stapelfeldt, Igor N. Cherepanov, Mikhail Lemeshko, Wolfgang Jäger, Jian Wu
Abstract
Rotational dynamics of D_{2} molecules inside helium nanodroplets is induced by a moderately intense femtosecond pump pulse and measured as a function of time by recording the yield of HeD^{+} ions, created through strong-field dissociative ionization with a delayed femtosecond probe pulse. The yield oscillates with a period of 185 fs, reflecting field-free rotational wave packet dynamics, and the oscillation persists for more than 500 periods. Within the experimental uncertainty, the rotational constant B_{He} of the in-droplet D_{2} molecule, determined by Fourier analysis, is the same as B_{gas} for an isolated D_{2} molecule. Our observations show that the D_{2} molecules inside helium nanodroplets essentially rotate as free D_{2} molecules.