We have observed infrared absorption peaks in solid nitrogen at hydrostatic pressures as high as 7 GPa at liquid-helium temperatures. The shift in the AlSb:CSb local vibrational mode is used to precisely calibrate the pressure. For all measured pressures we also observe the n3 vibrational mode of CO2 impurities. For pressures greater than 1.9 GPa, a peak appears which we attribute to a N-N stre...

We develop a quantitative theory of the ratio R of radiative to non-radiative de-excitation based on the Dexter-Klick-Russell criterion for the occurrence of luminescence. The model invokes three essential elements: a promoting mode, an accepting mode, and a set of lattice modes which ultimately absorb the vibrational energy. The ratio R is determined by the relative population of the relaxed e...

We consider a molecular single electron transistor coupled to a vibrational mode. For some values of the bias and gate voltage transport is possible only by absorption of one ore more phonons. The system acts then as a cooler for the mechanical mode at the condition that the electron temperature is lower than the phonon temperature. The final effective temperature of the vibrational mode depend...

Self-consistent normal mode analysis (SCNMA) is applied to heme c type cytochrome f to study temperature-dependent protein motion. Classical normal mode analysis assumes harmonic behavior and the protein mean-square displacement has a linear dependence on temperature. This is only consistent with low-temperature experimental results. To connect the protein vibrational motions between low and ph...

It has been suggested that iron in InP is compensated by a donor, related to the 2316 cm−1 local vibrational mode and previously assigned to the fully hydrogenated indium vacancy, VInH4. Using AIMPRO, an ab initio local density functional cluster code, we find that VInH4 acts as a single shallow donor. It has a triplet vibrational mode at around this value, consistent with this assignment. We a...

Normal mode analysis (NMA) has been proven valuable in modeling slow conformational dynamics of biomolecular structures beyond the reach of direct molecular simulations. However, it remains computationally expensive to directly solve normal modes for large biomolecular systems. In this study, we have evaluated the accuracy and efficiency of two approximate NMA protocols-one based on our recentl...

Decades of molecular dynamics and normal mode calculations suggest that the largest-scale collective vibrational modes of proteins span the picosecond to nanosecond time scale. Experimental investigation of these harmonic, low-amplitude motions, however, has proven challenging. In response, we have developed a vector network analyzer-based spectrometer that supports the accurate measurement of ...

We report a refined potential energy function for the ground electronic state of CS2 based on a least-squares fitting to several low-lying experimental vibrational frequencies. Energy levels up to 20,000 cm(-1) have been obtained on this empirical potential using the Lanczos algorithm and potential optimized discrete variable representation. Among them, 329 levels below 10,000 cm(-1) are assign...

The experimental observations of vibrational mode- and bond-selective chemistry at the gas-surface interface indicate that energy redistribution within the reaction complex is not statistical on the timescale of reaction. Such behavior is a key prerequisite for efforts to use selective vibrational excitation to control chemistry at the technologically important gas-surface interface. This paper...

The normal modes have been calculated for three kinds of low energy y-turn structures resulting from recent conformational energy calculations by Nkmethy. Frequencies have been computed for a y-turn, a mirror-related 7-turn, and an inverse y-turn of CH3-CO-(L-Ala),-NH-CH3, with n = 3 and n = 5 , and for certain l4 C and l5 N derivatives of the n = 3 molecule. Correlations are evident between am...