Showing papers by "Charles V. Shank published in 1988"
TL;DR: In this article, a 60-femtosecond pump pulse at 618 nanometers was used to study the primary photoprocesses in the light-driven transmembrane proton pump bacteriorhodopsin.
Abstract: Femtosecond optical measurement techniques have been used to study the primary photoprocesses in the light-driven transmembrane proton pump bacteriorhodopsin. Light-adapted bacteriorhodopsin was excited with a 60-femtosecond pump pulse at 618 nanometers, and the transient absorption spectra from 560 to 710 nanometers were recorded from -50 to 1000 femtoseconds by means of 6-femtosecond probe pulses. By 60 femtoseconds, a broad transient hole appeared in the absorption spectrum whose amplitude remained constant for about 200 femtoseconds. Stimulated emission in the 660- to 710-nanometer region and excited-state absorption in the 560- to 580-nanometer region appeared promptly and then shifted and decayed from 0 to approximately 150 femtoseconds. These spectral features provide a direct observation of the 13-trans to 13-cis torsional isomerization of the retinal chromophore on the excited-state potential surface. Absorption due to the primary ground-state photoproduct J appears with a time constant of approximately 500 femtoseconds.
497 citations
TL;DR: In this paper, the authors review the interesting advances and discuss the impact on new understanding in semiconductor physics and discuss their impact on the current understanding of nonequilibrium processes in semiconductors.
Abstract: Advances in ultrashort optical pulse measurement techniques have opened the way to the investigation of dynamic processes in semiconductors on a time scale previously inaccessible. Pulses as short as 6 femtoseconds have been generated and applied to the study of nonequilibrium processes in semiconductors. New optical electronic measurement techniques have provided the means for investigating transport on a femtosecond time scale. Novel techniques have been developed to study hot electrons in metals in the transient regime. In this contribution I will review these interesting advances and discuss the impact on new understanding in semiconductor physics.
1 citations
01 Jan 1988
TL;DR: A review of femtosecond optical pulses can be found in this paper, where the authors describe the state of the art and describe the application of FemTosecond techniques to the examination of nonequilibrium phenomena.
Abstract: Rapid progress has taken place in the generation and application of femtosecond optical pulses. The impact of these developments is being felt in a broad range of scientific fields including physics, chemistry, and biology. This paper reviews the state of the art and describes the application of femtosecond techniques to the examination of nonequilibrium phenomena.