In the past decades, femtosecond stimulated Raman spectroscopy (FSRS) has been gaining tremendous popularity in fundamental sciences stemming from chemistry to biology. It is capable of capturing both equilibrium and non-equilibrium structural information across a broad range of timescales with simultaneously high temporal and spectral resolutions. Femtosecond transient absorption spectroscopy...
County governments in the United States play important roles in the tax collection and public service provisions. Thus, a better understanding of the local government finances is closely related to the welfares of residents. In this dissertation, I provide two essays: in the first essay, I examine the fiscal impacts...
In this dissertation, I describe the experimental investigation of catching ions in superfluid helium droplets. The ultimate goal of our project is to build a coherent electron diffraction apparatus for atomic structure determination from oriented single macromolecules. This involves generating protein ions from electrospray ionization (ESI) and doping them in...
Ultrafast spectroscopy can exploit the structure-function relationship of chemical- and biological-based systems. More specifically, femtosecond stimulated Raman spectroscopy (FSRS) provides ground- and excited-state vibrational information with simultaneously high spectral (spatial) and temporal resolutions. The electronic counterpart, femtosecond transient absorption (fs-TA), complements FSRS data analysis as part of a comprehensive approach...
Ultrafast spectroscopy has recently gained momentum as a powerful, noninvasive characterization toolset capable of studying a diverse array of samples with applications in chemistry, physics, biology, engineering, and more. Two popular ultrafast spectroscopic techniques include femtosecond transient absorption (fs-TA) and femtosecond stimulated Raman spectroscopy (FSRS). The latter of these techniques...
Photoactivated biomedical tools like fluorescent biosensors and optogenetic proteins have increased in popularity due to the precision targeting and activation used for in vivo applications. In nature, the initially discovered parent proteins exhibit properties such as fluorescence quantum yield (FQY), fluorescence color, and photoswitching dynamics that are unfavorable in mammalian...
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Chong Fang
“The journey of 1000 miles begins with a single step.” – Miyamoto Musashi
In this dissertation, excited state proton transfer (ESPT) and its inhibition in solution and protein environments are revealed using both femtosecond transient absorption (fs-TA) spectroscopy and femtosecond stimulated Raman spectroscopy (FSRS). Using a tunable Raman pump to enhance transient vibrational features of the photoacidic chromophore HPTS in methanol and methanol...
Femtosecond stimulated Raman spectroscopy (FSRS) is an ultrafast vibrational technique which allows rapid collection of Raman spectra with simultaneously high temporal and spectral resolution. With the recent development of FSRS methodology, three FSRS techniques (conventional, tunable, and anti-Stokes) have been implemented in our laboratory to dissect the excited state structural...
To obtain a mechanistic understanding of the chemical processes, techniques that offer a frame-by-frame visualization of molecular structure during a reaction are of vital importance. Numerous efforts and advances have been made in order to acquire such vivid molecular “movies”, especially in the electronic excited state. Ultrafast molecular spectroscopy method...
Femtosecond stimulated Raman spectroscopy (FSRS) is a powerful ultrafast technique which can track photoinduced excited state structural events on femtosecond (fs) to picosecond (ps) timescales. In addition to high temporal and spectral resolutions, FSRS provides a broad spectral window from ca. 100—2000 cm-1 for detection, enabling the direct mapping of...