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The absorption spectra of isotopically substituted carbon disulfide, i.e., 13C32S2 and 12C34S2, cooled in supersonic expansion are reported here and compared with the spectrum of the natural isotope. Cooling these samples eliminated spectral congestion due to inhomogeneous factors and yielded measurements of frequencies and isotopic shifts of bands of 13C32S2 and 12C34S2 relative to 12C32S2. The spectrum obtained is interpreted to reflect a transition from a linear ground state to a bent excited state up to ∼49 000 cm-1 and to a quasilinear excited state above this energy. [ABSTRACT FROM AUTHOR]

The observed electronic line broadening of the X→B (6s Rydberg) absorption spectrum of CH3I vapor in moderate to high pressures (55–140 atm, reduced densities ∼0.08–0.14) of Ar and CH4 is analyzed via molecular dynamics simulations. Good fits to the absorption line shapes are found in this pressure/density range for a given set of ground and excited state solute–solvent potential parameters in the static limit, i.e., the absorption linewidths and shapes are dominated by inhomogeneous broadening on the time scale of the decay of the dipole correlation function. The pressure dependence of these absorption line shape changes is explained in terms of the shape of the solute–solvent ground-excited state difference potential. Consistent with the static limit description at these moderate to high pressures, the corresponding transition energy correlation function, a quantity of central importance in stochastic and Brownian oscillator line shape theories, decays on a much longer time scale than the inverse absorption widths. At moderate to high pressures, simulations find relatively long-lived solvent clusters surrounding the CH3I solute. The slow decay of the energy correlation functions, and hence the validity of the static approximation, is attributed to these cluster dynamical time scales. At bath pressures lower than observed here, MD simulations reveal that the static limit is no longer valid and satellite bands, due to an underdamped solvent response, are found. The evolution of a Gaussian optical line shape at higher densities is discussed with respect to the difference potential shape, the number density, and the central limit theorem. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Understanding the role of neurons in encoding and transmitting information is a major goal in neuroscience. This requires insight on the data-rich neuronal spiking patterns combined, ideally, with morphology and genetic identity. Electrophysiologists have long experienced the trade-offs between anatomically-accurate single-cell recording techniques and high-density multi-cellular recording methods with poor anatomical correlations. In this study, we present a novel technique that combines large-scale micro-electrode array recordings with genetic identification and the anatomical location of the retinal ganglion cell soma. This was obtained through optogenetic stimulation and subsequent confocal imaging of genetically targeted retinal ganglion cell sub-populations in the mouse. With the many molecular options available for optogenetic gene expression, we view this method as a versatile tool for matching function to genetic classifications, which can be extended to include morphological information if the density of labelled cells is at the correct level.