Resonance enhancement has been increasingly employed in the emergent femtosecond stimulated Raman spectroscopy (FSRS) to selectively monitor molecular structure and dynamics with improved spectral and temporal resolutions and signal-to-noise ratios. Such joint efforts by the technique- and application-oriented scientists and engineers have laid the foundation for exploiting the tunable FSRS...
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...
Imaging Ca²⁺ dynamics in living systems holds great
potential to advance neuroscience and cellular biology. G-GECO1.1
is an intensiometric fluorescent protein Ca²⁺-biosensor with a Thr-Tyr-Gly chromophore. The protonated chromophore emits green
upon photoexcitation via excited-state proton transfer (ESPT). Upon
Ca²⁺ binding, a significant population of the chromophores becomes
deprotonated. It...
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...
The demand for the development of sustainable energy is an all time high as we burn through limited fossil fuel reserves and as environmental concerns rise every year. Renewable energy sources such as wind and solar power have limitations due to inconsistent power supply that cannot meet the regular needs...
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...
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...
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...
In this thesis, I present a new method we developed to study low frequency (< 700 cm⁻¹) vibrational dynamics: Time-resolved third-harmonic generation (TRTHG) spectroscopy. Among a variety of vibrational spectroscopy techniques, TRTHG differentiates itself with robustness, versatility, and simplicity. In TRTHG experiment, that involves only two ultrashort laser pulses, the...
The increase in the demand for energy is estimated to be 28 TW by a year of 2050, which is twice of the energy produced in 2010, in response to the unprecedented growth of the global population. Current energy market is heavily relying on the fossil fuel, which brings the...