Show simple item record

dc.contributor.advisorUmapathy, Siva
dc.contributor.authorRoy, Khokan
dc.date.accessioned2018-05-25T04:54:40Z
dc.date.accessioned2018-07-30T15:02:55Z
dc.date.available2018-05-25T04:54:40Z
dc.date.available2018-07-30T15:02:55Z
dc.date.issued2018-05-25
dc.date.submitted2017
dc.identifier.urihttp://etd.iisc.ac.in/handle/2005/3610
dc.identifier.abstracthttp://etd.iisc.ac.in/static/etd/abstracts/4479/G28480-Abs.pdfen_US
dc.description.abstractThe subject of this thesis is the design and development of a unified set up for femtosecond transient absorption and ultrafast Raman loss spectroscopy and demonstrate its potential in capturing the ultrafast photophysical and photochemical processes with excellent time and frequency resolution. Ultrafast spectroscopy has been serving as a powerful tool for understanding the structural dynamical properties of molecules in the condensed and gas phase. The advent of ultrashort pulses with their high peak power enables the laser spectroscopic community to study molecular reaction dynamics and photophysics that happen at extremely short timescales, ranging from picosecond to femtosecond. These processes can be measured with extremely high time resolution, which helps to resolve the under-lying molecular process. But in order to understand the global mechanism of the underlying molecular processes, we have to resolve the nuclear dynamics with the proper frequency resolution. However, achieving both, time and frequency resolutions simultaneously is not possible according to the Heisenberg uncertainty principle. Later, this limitation was overcome by femtosecond stimulated Raman spectroscopy (FSRS), a third order non-linear Raman spectroscopy. In this thesis we introduced the ultrafast Raman loss spectroscopic (URLS) technique which is analogous to FSRS, offering the modern ultrafast community to resolve molecular processes with better signal-to-noise ratio along with proper time and frequency resolution. We demonstrate the experimental procedure including the single shot detection scheme to measure whitelight background, ground state Ra-man, transient absorption and transient Raman in shot-to-shot detection fashion. URLS has been applied to understand the excited state planarization dynamics of 1,4-bis(phenylethynyl)benzene (BPEB) in different solvents. In addition, excitation wavelength dependent conformational reorganization dynamics of different sub-sets of thermally activated ground state population of BPEB are also discussed. Using the same techniques along with femtosecond transient absorption, we demonstrate the ultrafast vibrational energy transfer and the role of coherent oscillations of low frequency vibrations on the solution phase photo-isomerization of trans-stilbene from an optically excited state. The effects of solvents on the coherent nuclear motion are also discussed in the context of reaction rates. 2en_US
dc.language.isoen_USen_US
dc.relation.ispartofseriesG28480en_US
dc.subjectBis(phenylethynyl)benzene (BPEB)en_US
dc.subjectFemtosecond stimulated Raman Spectroscopy (FSRS)en_US
dc.subjectUltrafast Raman Loss Spectroscopy (URLS)en_US
dc.subjectVibrational Spectroscopyen_US
dc.subjectUltrafast Spectroscopyen_US
dc.subjecttrans-Stilbeneen_US
dc.subjectTime-Resolved Spectroscopyen_US
dc.subjectTime Resolved Absorptionen_US
dc.subjectFemtosecond Stimulated Raman Scatteringen_US
dc.subjectFemtosecond Transient Absorptionen_US
dc.subjectUltrafast Stimulated Raman Loss Spectroscopyen_US
dc.subjectUltrafast Raman Loss Studyen_US
dc.subjectRaman Loss Spectroscopic Studiesen_US
dc.subject.classificationInorganic and Physical Chemistryen_US
dc.titleUltrafast Raman Loss Spectroscopic Investigations of Excited State Structural Dynamics of Bis(phenylethynyl)benzene and trans-Stilbeneen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.disciplineFaculty of Scienceen_US


Files in this item

This item appears in the following Collection(s)

Show simple item record