Volume 129, Issue 4, 28 July 2008
Index of content:
Investigating isomerization reactions in solid state by using simultaneous high overtone pumping and Raman detection129(2008); http://dx.doi.org/10.1063/1.2955985View Description Hide Description
Formation of the unstable cis-formic acid in solid argon matrix is induced by direct excitation of the transition of the vibration of the trans-formic acid. The experiment utilizes strongly focused laser beam that produces relatively high isomerization rate despite the low cross section of the absorption. Raman spectroscopy in a backscattering geometry is used for detection of the reactants and the products. This experimental arrangement allow us to use the same laser source for simultaneous pumping and Raman excitation, and it also guarantees that the excited and probed volumes overlap. The presented method has a high potential for solid state investigations of chemical reactions on the ground electronic state.
Temporal characteristics of the and thiophosgene in the gas phase: Comparison of the decay with theoretical predictions129(2008); http://dx.doi.org/10.1063/1.2963037View Description Hide Description
The picosecond optical-optical double resonance experiment in a supersonic free jet as well as the vapor-phase phosphorescence indicates that the decay of belongs to the intermediate case of the classification scheme for electronic relaxation. The pre-exponential ratio in the biexponential decay is much greater under picosecond excitation than under nanosecond excitation. In vapor phase at low pressure, the phosphorescence exhibits a decay time that varies with the coherence width of the laser used for excitation. Both the and the decay times of depend strongly on temperature, indicating that Coriolis coupling plays an important role in mode mixing (intramolecular vibrational redistribution).
A direct approach to study radiative emission from triplet excitations in molecular semiconductors and conjugated polymers129(2008); http://dx.doi.org/10.1063/1.2961010View Description Hide Description
Using the recently discovered time-dependent spin-orbit-photon interaction operator and first order perturbation theory, the rate of spontaneous emission from triplet excitations is derived within the two-level approximation for organic molecular solids and conjugated polymers. The calculated rates and corresponding radiative lifetimes agree very well with the known experimental results. Present results are compared with those obtained through the traditional approach of the second order perturbation theory in some molecular crystals and found to be in better agreement with experiments.
129(2008); http://dx.doi.org/10.1063/1.2957492View Description Hide Description
A planar hard surface covered with elongated stiff rodlike particles in shear flow is considered in the low-Reynolds-number regime assuming low particle surface coverage. The particles are modeled as straight chains of spherical beads. Multipole expansion of the Stokes equations (the accurate HYDROMULTIPOLE algorithm) is applied to evaluate the hydrodynamic force exerted by the fluid on the rodlike particles, depending on their shape, i.e., on the number of beads and their orientation with respect to the wall and to the ambient shear flow.
129(2008); http://dx.doi.org/10.1063/1.2958220View Description Hide Description
Quantum conditions on the control of dynamics of a system coupled to an environment are obtained. Specifically, consider a system initially in a systemsubspace of dimensionality , which evolves to populate systemsubspaces, of dimensionalities , . Then, there always exists an initial state in that does not evolve into if , where is the number of operators in the Kraus representation. Note, significantly, that the maximum can be far smaller than the dimension of the bath. If this condition is not satisfied, then dynamics from that avoids can only be attained physically under stringent conditions. An example from molecular dynamics and spectroscopy, i.e., donor to acceptor energy transfer, is provided.