Excitation of Molecules by Strong Laser Fields

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Understanding how light interacts with matter is important in scientific research and applications. For example, one of the most vital processes in nature is the absorption of solar energy by plants in photosynthesis. Scientists use lasers to make forms of light with special properties that are used in research and technologies such as optical communications. The research supported in this project will investigate how extremely intense laser light interacts with small molecules. Insight will be gained into three main areas. 1) When molecules interact with intense laser light, the molecules can, in turn, generate new types of radiation with unique properties. In this case, the generated light can have very short wavelengths and very short durations in time. These properties can be used to study very fast processes such as chemical reactions. 2) Intense laser light can drive processes in molecules in a way that allows more to be learned about the structure of molecules. 3) Intense laser light can be used to control the vibrational motions of molecules, which is one of the properties of molecules used for storing and transferring energy. Energy transfer in molecules will be better understood at the fundamental level by controlling molecular vibrations. 4) The techniques and instrumentation used in these experiments provide excellent training for students to acquire skills used in many industries and research laboratories.This project focuses specifically on strong field processes that give rise to excitation in molecules. Although the excitation of molecules by strong fields is ubiquitous, there is not nearly as much experimental and theoretical work on this compared to other areas of strong field physics. Moreover, the range of possible mechanisms for excitation remains largely unexplored. However, there is increasing interest in this field, as one pathway to excitation involves inner orbital ionization. It turns out that excitation can be so significant that it can lead to lasing in the atmosphere by intense laser beam filaments. Nevertheless, the exact process by which inversions are formed in nitrogen is still not fully understood. The common theme to all of these goals is to understand the excitation of molecules by strong laser fields and the dependence of this excitation on internuclear separation. Successful outcomes of these experiments should greatly expand the understanding of how intense light interacts with matter, particularly regarding molecular structure and dynamics.