Spectroscopic and dynamic properties of molecules adsorbed on surfaces.
Item
-
Title
-
Spectroscopic and dynamic properties of molecules adsorbed on surfaces.
-
Identifier
-
AAI9630495
-
identifier
-
9630495
-
Creator
-
Ozcelik, Serdar.
-
Contributor
-
Adviser: Daniel L. Akins
-
Date
-
1996
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Chemistry, Physical
-
Abstract
-
The photophysical properties of monomeric cyanines are studied because of the utility of such measured parameters as reference to spectroscopy and dynamics of the J-aggregates.;The structure and excited-state dynamics of J-aggregates of 1,1{dollar}\sp\prime{dollar}-diethyl-2,2{dollar}\sp\prime{dollar}-cyanine, also known as pseudoisocyanme (PIC), adsorbed onto a vesicle surface is studied. The results of spectrophotometric titrations for the interconversion of monomeric and aggregated 2,2{dollar}\sp\prime{dollar}-cyanine and photophysical parameters of two putative adsorbed aggregates species (mono-cis- and all-trans conformers of the J-aggregates, relating to their makeup from mono-cis and all-trans stereoisomers, respectively). Superradiance and energy transfer are dominant features controlling photophysical processes. It is suggested that structure plays the crucial role in excited state dynamics.;A time-resolved, picosecond fluorescence spectroscopic study of benzimidazolocarbocyanine (BIC) adsorbed on a silica surface is presented. At the beginning, excitons are created in subpicoseconds. When two excitons close to each other, exciton-exciton interactions take place. As a result of the interaction, new states, specifically, the biexciton states in addition to the one-exciton state are created: a blue-shifted state relative to the one-exciton state, and a red-shifted state relative to the one-exciton. A kinetic model is proposed for the one-exciton and biexciton states.;The excited-state properties of 9-phenyl dibenzothiacarbocyanine (DBTC) aggregates is studied. The J-aggregate formed in homogeneous solution shows resonance fluorescence that indicates free exciton luminescence. The J-aggregates adsorbed onto silica surface show a Stokes shift. This Stokes-shift indicates the aggregate structure in the excited-state should be changed comparing to the ground-state structure. The J-aggregate formed in homogeneous solution studied has enhanced fluorescence, while another one adsorbed onto a silica surface shows nonradiative relaxations dominant in the excited-state.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
