Ultra high resolution 4-D spatio-temporal imaging using intense laser pulses
X-ray diffraction and electron microscopy have been the conventional
means for imaging matters to achieve spatial resolution of better than
the atomic scale (Angstroms) for long time.Recently, various methods
capable of resolving the temporal as well as the spatial information
have been developed to analyze matter transitions.
New techniques for imaging transient matters with higher temporal
resolutions are growing increasingly desirable. In this project,
we will develop theoretical and computational methods for
high resolution 4-D spatio-temporal imaging of atoms and molecules
using intense ultrashort infrared laser pulses. Spatial resolution of
the atomic scale (Angstroms) and temporal resolution of the order of
the electron orbital period in molecules (atto seconds) can be achieved
using rescattering electrons produced from molecules exposed to intense
laser pulses (See Figure 1). This new technique should open up a route
to the time-resolved study of electron dynamics in matter transition
and promote deeper understanding of the laser-matter interaction.
Schematic of chemical imaging with infrared lasers. (a) The electric field (E) and the vector potential (A) of a typical five-cycle infrared laser pulse. (b) Schematic of using backward rescattering process to image the molecule by its own electron. First, the electron gets tunnel ionized near "a" at the peak of the electric field. It returns to recollide with the target near "b" which corresponds to the peak of the vector potential and get scattered backward to imprint the target structure on the detector. Electrons ionized near "a' " instead would imprint the image on a detector on the left (not shown).