Light-induced states in attosecond transient absorption spectra of laser-dressed helium

Shaohao Chen,1,* M. Justine Bell,2,3,* Annelise R. Beck,2,3 Hiroki Mashiko,2 Mengxi Wu,1 Adrian N. Pfeiffer,2,3 Mette B. Gaarde,1 Daniel M. Neumark,2,3 Stephen R. Leone,2,3,4 and Kenneth J. Schafer1 1Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA 2Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 3Department of Chemistry, University of California, Berkeley, California 94720, USA 4Department of Physics, University of California, Berkeley, California 94720, USA (Received 5 September 2012; revised manuscript received 26 November 2012; published 17 December 2012)