MRSEC Seminar

Behavior of Atoms and Molecules in Strong Electromagnetic Fields:
From X-ray Switches to Hollow Atoms

Linda Young

Argonne National Laboratory

Thursday, May 14, 4:00 pm

Ryan Hall (Nano) 4003

Control of x-ray processes using intense optical lasers represents an emerging scientific frontier---one which combines x-ray physics with strong-field laser control. While the past decade has produced many examples where phase- and amplitude-controlled lasers at optical wavelengths are used to manipulate molecular motions, the extension to control of ultrafast, intraatomic, inner-shell processes is quite new. Gas phase systems are particularly suitable for illustrating the basic principles underlying combined x-ray and laser interactions. We have studied three scenarios by which strong electromagnetic fields can be used to modify resonant x-ray absorption in a controlled manner: (1) Ultrafast-field ionization of atoms at laser intensities in the range 10¹⁴-10¹⁵ W/cm²; (2) laser-induced x-ray transparency of inner-shell resonances by laser dressing at 10¹²-10¹³ W/cm²; and (3) control of resonant x-ray absorption by molecules through laser-induced alignment at 10¹² W/cm². These phenomena have been demonstrated recently using x-ray microprobe methodology at the Advanced Photon Source and the Advanced Light Source. Due to the rapid and controllable repsonse of electrons in free atoms and molecules, one can realize novel technologies, such as femtosecond x-ray switches and modulators. Looking toward the future, the world’s first x-ray free electron laser, the Linac Coherent Light Source (LCLS) at Stanford, lased in April 2009, ushering in an exciting era of discovery as we explore the response of matter to intense laser fields at short wavelengths.

Host: Professor Tamar Seideman, Chemistry