Femtosecond laser excitation and spectroscopy of liquid helium

Alexander Vict Benderskii; Ruben Zadoyan; Nikolaus Schwentner; Vartkess Ara Apkarian

doi:10.1117/12.306135

24 April 1998 Femtosecond laser excitation and spectroscopy of liquid helium

Alexander Vict Benderskii, Ruben Zadoyan, Nikolaus Schwentner, Vartkess Ara Apkarian

Proceedings Volume 3273, Laser Techniques for Condensed-Phase and Biological Systems; (1998) https://doi.org/10.1117/12.306135
Event: Optoelectronics and High-Power Lasers and Applications, 1998, San Jose, CA, United States

Abstract

Femtosecond laser pulses focused inside liquid helium initiate an excitation sequence that leads to formation of molecular Rydberg states He₂ detected by fluorescence spectroscopy. Unlike in the case of longer laser pulses, the excitations may be created in a controllable way, at light intensities below dielectric breakdown. The initial step is ionization of He atoms, as demonstrate by charge separation in external electric field. A sequence of the subsequent processes is proposed, which accounts for rapid production of He₂, in less than 10 ns, observed by nanosecond time- resolved laser induced fluorescence following the excitation pulse. the lowest triplet state excimers He₂(³a), probed in the latter experiment, are long-lived and survive in concentrations of the order of 10¹¹-10¹² cm^-3 on a millisecond time scale. Femtosecond time- resolved spectroscopy was performed on He₂* molecules in liquid He, using the pump-probe sequence He₂*(³a) + 790 nm yields He₂*(³c), He₂*(³c) + 790 nm yields He₂*(³f). The observed decay of the transient signals with characteristic time 3.5 ps is thought to be due to solvent motion corresponding to the relaxation of the liquid helium 'bubble' around the intermediate He₂*(³c) state.

Citation Download Citation

Alexander Vict Benderskii, Ruben Zadoyan, Nikolaus Schwentner, and Vartkess Ara Apkarian "Femtosecond laser excitation and spectroscopy of liquid helium", Proc. SPIE 3273, Laser Techniques for Condensed-Phase and Biological Systems, (24 April 1998); https://doi.org/10.1117/12.306135

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available