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No description available.

No description available.

No description available.

No description available.

The main focus of this work is using the infrared-infrared (IR-IR ) double resonance spectroscopic technique to study the 2³Πg, a³Σ⁺u triplet ground states, and the A¹Σ⁺u ~ b³Πu coupled states of the Rubidium dimer molecule. The initial analysis of the 2³Πg state involved separated analysis of the rotational and vibrational Bv and Gv functions to extract the molecular Dunham coefficients from the data. This was to avoid cross correlations between rotational and vibrational parameters because there was limited amount of rotational energy level data which included in addition perturbations between this state and other electronic states in the same region. An initial RKR potential energy curve was constructed based on this analysis. Subsequently this approach was augmented by a joint analysis of the 2³Πg state and the triplet ground state. This analysis was based on bound-free spectra, i.e. fluorescence from bound levels of the upper state to the continuum of the lower state. We present a comparison of these two approaches to the data analysis by testing the resulting potential energy functions through comparison of the calculated ro-vibrational energies against the observed energy level values The fluorescence from a discrete ro-vibrational level of the a bound upper state 2³Πg also includes transitions to discrete bound ro-vibrational levels of the triplet ground state (bound-bound emission). Accurate determination of the transition frequencies of the observed fluorescence spectroscopic lines allowed us to construct a reliable potential energy function that augmented our previous results on this state and corrected misinterpretation of that data in the literature. Similar infrared-infrared (IRIR) double resonance excitation of the 3¹Σ⁺g state was also used to observe resolved fluorescence spectra to the A~b states coupled by strong spin-orbit interaction. From the IRIR resolved fluorescence, we have filled the gap in the data range 12000cm-1 to 14000cm-1 of these coupled states for the Ω=0u⁺ component. / Physics

Biomolecules function only in aqueous environments and their dynamics are strongly influenced by physiological conditions including the temperature and the presence of co-solutes. The presence of biomolecules in aqueous solutions will change the dynamics and structure of water, and as a response, water will form hydration layers around biomolecules. The dynamics of hydration water, as well as hydrated proteins, lead to translation, rotation, and oscillating dipoles that, in turn, give rise to absorption in the megahertz-to-terahertz frequencies. However, the strong absorption of water in this frequency range leads to a significant challenge in obtaining terahertz dielectric spectra of aqueous biomolecular solutions. In response, I have employed a high sensitivity terahertz frequency-domain spectroscopy to overcome these issues on a large range of frequencies from 10 MHz to 1.12 THz. The high dynamical range of the system combined with a variable-path-length cell allows precise measurement of the complex dielectric response of the solutions. Employing Debye and Lorentzian approximations, I have decomposed contributions of the dielectric response of the solutions. The structure and dynamics of hydration shells and hydrated biomolecules have been identified. Performing experiments on a number of biomolecules have verified the certainty of the methods, thus, enriching the knowledge of the biological science of dynamics and functions of biomolecules. / Doctor of Philosophy / Biomaterials are essential for life, including all elements present in cells and organisms, and contribute to the living biological processes. Biomaterials, consisting of a diverse range of biomolecules, have traditionally been characterized in a wide range of approaching methods based on biological, chemical, and physical methodologies. This study investigates the molecular dynamics of biomolecules in native living environments to explore physics- and mechanics-based insights into their biological functions. Biomaterials together with water molecules perform their functions through molecular translations, rotations, and collective motions. To explore these dynamics, a home-built terahertz spectroscopy with high sensitivity has been utilized to characterize the dynamics of biomolecular aqueous solutions in the frequency range from megahertz to terahertz. The collected complex dielectric responses of the solutions have been examined through physical models to map out structures and dynamics of hydration shells and, then, the dynamics of hydrated biomolecules have been determined. The successfully investigating results in the dynamics of solvents from three different types of proteins and ionic solutions reveal critical information on hydrated biomolecular dynamics and biomolecule–water interactions, which impact the biochemical functions and reactivity of biomolecules.

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No description available.

Abstract Chalcogenide glasses and films are excellent candidates for near-infrared guiding configurations in opto-e]ectronics due to the ir high transmission. Their photosensitivity allows waveguide creation by standard lithography or one- and two-photon writing. The near-infrared Raman spectra of a series of As-S(Se) glasses are analyzed using spectral deconvolution and correlated with the molecular structure. Contributions due to As­ (S,Se)3 pyramjdal subunits as well as homopolar Se-Se and S-S bonds are determined. Photoinduced molecular changes in waveguide structures are probed by Raman scattering employing guided mode excitation. A new approach is demonstrated to optically interrogate composite layers where a chalocogenide waveguide provides the substrate and the guiding layer for a biomolecular film whose Raman spectrum is desired. Hydrophilic chalcogenide surfaces were prepared by exposure to 0 ₂ plasma and characterized by XPS spectroscopy. Thin layers of the photo-active protein bacteriorhodopsin were deposited on As₂S3 waveguides and observed by scanning electron and atomic force microscopy. The evanescent wave excited near-infrared Raman spectrum is measured in-situ providing a molecular probe of the chromophore and the light-adaptedstate. This novel technique offers potential for protein monolayer characterization and bio-sensors.