Development of Frequency Domain Multidimensional Spectroscopy with Applications in Semiconductor Photophysics

摘要

Coherent multidimensional spectroscopy (CMDS) encompasses a family of experimental strategies involving the nonlinear interaction between electric fields and a material under investigation. This approach has several unique capabilities: (1) resolving congested states, (2) extracting spectra that would otherwise be selection-rule disallowed, (3) resolving fully coherent dynamics, (4) measuring coupling, and (5) resolving ultrafast dynamics.;CMDS can be collected in the frequency or the time domain, and each approach has advantages and disadvantages. Frequency domain ``Multi-resonant'' CMDS (MR-CMDS) requires pulsed ultrafast light sources with tunable output frequencies. These pulses are directed into a material under investigation. The pulses interact with the material, and due to the specific interference between the multiple fields the material is driven to emit a new pulse: the MR-CMDS signal. This signal may have a different frequency and/or direction than the input pulses, depending on the exact experiment being performed. The MR-CMDS experiment involves tracking the intensity of this output signal as a function of different properties of the excitation pulses. These properties include (1) frequency. (2) relative arrival time and separation (delay), (3) fluence, and (4) polarization, among others. Thus MR-CMDS can be thought of as a multidimensional experimental space, where experiments typically involve explorations in one to four of the properties above.;Because MR-CMDS is a family of related-but-separate experiments, each of them a multidimensional space, there are special challenges that must be addressed when designing a general-purpose MR-CMDS instrument. These issues require development of software, hardware, and theory. Part I: Background introduces relevant literature which informs on this development work. Part II: Development presents five strategies used to improve MR-CMDS: (1) processing software, (2) acquisition software (3), active artifact correction, (4) automated OPA calibration, and (5) finite pulse accountancy. Finally, Part III: Applications presents four examples where these instruments, with these improvements, have been used to address chemical questions in semiconductor systems.