Laser Alignment in Complex Media

Monday, September 24, 2012 -
4:00pm to 5:00pm
Tamar Seideman
Speaker's Institution: 
Northwestern University

Nonadiabatic alignment is a coherent approach to control over the spatial properties of molecules, wherein a short, moderately-intense laser pulse is applied to populate a broad rotational wavepacket with fascinating properties. In the limit of small isolated molecules, nonadiabatic alignment has evolved in recent years into an active field of theoretical and experimental research with a rich variety of applications. Our goal in the present talk is to extend the alignment concept to complex systems, including large polyatomic molecules, dissipative media, nonrigid systems, molecular assembly, and molecular junctions. Following a brief review of the essential physics underlying alignment, we consider the case of asymmetric top molecules, where alignment overcomes the mechanisms that render the rotations unstable in the classical limit. Next we focus on dense media, and illustrate the application of rotational wavepackets as a probe of the dissipative properties of the environment. We extend alignment to control the torsional motions of polyatomic molecules, and apply torsional control to manipulate charge transfer events in solutions, suggesting a potential route to light controlled molecular switches. Turning to interfaces, we introduce a route to guided molecular assembly, wherein laser alignment is extended to induce long-range orientational order in molecular layers. Finally, we combine the nonadiabatic alignment concept with recent research on nanoplasmonics and on conductance via molecular junctions to develop an approach to coherent control of transport in the nanoscale.