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A GAAA tetraloop domain and receptor domain are connected by a single-strander A7 linker to investigate the metal ion dependence, kinetics and thermodynamics for the isolated tertiary interaction in RNA of the GAAA-tetraloop motif. Studies of docking induced using a variety of metal ions show that the single-stranded region functions primarily as a flexible tether and inhibition of docking by oligonucleotides complementary to the linker is investigated.

A transient absorption spectroscopic study of the photosensitization of differently sized TiO2 nanoparticles by anthracenecarboxylic acid dye molecules is reported.

The development of dye-sensitized semiconductor systems spawned scientific interest on factors affecting back electron transfer dynamics. Experiments were conducted to characterize the Marcus inverted region. The effects of water on the forward and back electron transfers in 9-anthracenecarboxylic acid (9AC) bound to titanium dioxide particles were also examined. The findings indicated a slight increase in back electron transfer reactions upon the addition of water and confirmed the Marcus inverted region as the site where high rates of this reaction occur.

Discusses the use of ultrafast laser spectroscopy to characterize the low frequency acoustic breathing modes of gold particles. Impulsive excitation of modes by rapid heating of the particle lattice that occurs after laser excitation; Processes involved in the excitation mechanism; Inverse proportion of measured frequencies of acoustic modes to the particle radius.

Observes quantum beats due to coherently prepared acoustic vibrational modes for 14 to 17 nanometer diameter gold particles. Production of quantum beats in transient absorption; Attribution of quantum beats to coherent acoustic vibrational motion in particles; Redistribution of energy from impulsively excited acoustic vibrations to phonon modes.

An attempt is made to investigate the laser-induced melting and alloy formation in AucoreAgshell nanoparticles and the associated spectral changes. The thresholds for laser-induced transformations are lower for picosecond laser pulses compared to nanosecond laser pulses.

The photophysics of metal nanoparticles, that include Au particles with sizes ranging from 2nm diameter to 120nm diameter, and bimetallic core-shell particles composed of Au, Ag, Pt and/or Pb are investigated. The findings indicate that for Au the time scale for electron-phonon coupling does not depend on size, in contrast to metals such as Ga and Ag.

A study was conducted to analyze the influence of structure on the electron transfer reactions between anthracene dyes and TiO2 nanoparticles. Controlled hydrolysis was carried in water of titanium(IV) isopropoxide to prepare anatase TiO2 nanoparticles. The Perkin-Elmer Lambda 6UV-vis spectrometer was then utilized to obtain steady-state absorption spectra. Results indicated that the preparation of the particles influenced the time constants for electron transfer for semiconductor particles-bound dye molecules.

Femtosecond transient absorption spectroscopic studies were conducted to investigate the electron-phonon relaxation dynamics in nanometer-sized gold and silver (Ag) particles. Simple spectral calculations were combined with two-temperature model for electron-phonon equilibration. The findings showed that strong transient bleach at the peak of the plasmon band are caused by pump-laser-induced heating and that the transient bleach signal for Ag increased after a high pump laser power. Moreover, electron-phonon coupling in small metal particles can only be obtained at low excitation levels.

Graphene oxide (GO) is an important precursor in the production of chemically derived graphene. During reduction, GO's electrical conductivity and band gap change gradually. Doping and chemical functionalization are also possible, illustrating GO's immense potential in creating functional devices through control of its local hybridization. Here we show that laser-induced photolysis controllably reduces individual single-layer GO sheets. The reaction can be followed in real time through sizable decreases in GO's photoluminescence efficiency along with spectral blueshifts. As-produced reduced graphene oxide (rGO) sheets undergo additional photolysis, characterized by dramatic emission enhancements and spectral redshifts. Both GO's reduction and subsequent conversion to photobrightened rGO are captured through movies of their photoluminescence kinetics. Rate maps illustrate sizable spatial and temporal heterogeneities in sp(2) domain growth and reveal how reduction "flows" across GO and rGO sheets. The observed heterogeneous reduction kinetics provides mechanistic insight into GO's conversion to chemically derived graphene and highlights opportunities for overcoming its dynamic, chemical disorder.