In this chapter we review recent advances in theoretical methods to understand and rationalize anharmonic vibrational spectroscopy (IR-MPD and IR-PD) and collision induced dissociations (CID) in the gas phase. We focused our attention on the application of molecular dynamics-based methods. DFT-based molecular dynamics was shown to be able to reproduce InfraRed Multi-Photon Dissociation (IR-MPD)...

We propose a new chemical detection technique in which an analyte's vibrational frequencies are interrogated directly using an array of nanomechanical resonators. This "nanomechanical resonance spectroscopy" (NRS) could permit label-free chemical detection, combining the high sensitivity of nanomechanical approaches with the high selectivity of traditional spectroscopy. A computational proof of...

The electronic vibrational damping rates of the CN and CO internal stretch modes on the (111) surfaces of Ag, Cu, Au, and Pt were calculated using density functional theory calculations. Our calculated damping rates are in excellent agreement with experimental data obtained from pump-probe laser spectroscopy. The striking difference in trends and magnitudes between the internal stretch modes of...

In J-aggregates of cyanine dyes, closely packed molecules form mesoscopic tubes with nanometer-diameter and micrometer-length. Their efficient energy transfer pathways make them suitable candidates for artificial light harvesting systems. This great potential calls for an in-depth spectroscopic analysis of the underlying energy deactivation network and coherence dynamics. We use two-dimensional...

Direct measurements of the lifetimes of He(79)Br(2) and Ne(79)Br(2) B-state vibrational levels 10 < or = nu' < or = 20 have been performed using time-resolved optical pump-probe spectroscopy. The values do not obey the energy gap law for direct vibrational predissociation. For both molecules, the dissociation rate for nu'=11 is much faster than for nu'=12, and the nu'=13 rate is also faster tha...

Vibrational spectroscopy (VS) is the analysis of molecular properties based on vibrations at the molecular level and it is highly selective1. VS produces a spectral fingerprint of a material, such as an active pharmaceutical ingredient (API), so is well-suited to both identify and verify the API raw material and its presence in a final product. There are three related analytical techniques that...

Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy was applied in the analysis of vibrational and low lying electronic transitions of a triplet ground state cobalt(III) coordination compound. The spectroscopic measurements were performed on the tetrabutylammonium salt of (6S,7S)-1,3,5,8,10,12-hexaaza-2,4,9,11-tetraoxo-6,7-diphenyl-dodecanato(4-)cobaltate(III) in D...

Vibrational lifetimes of hydrogen and deuterium related bending modes in semiconductors are measured by transient bleaching spectroscopy and high-resolution infrared absorption spectroscopy. We find that the vibrational lifetimes follow a universal frequency-gap law; i.e., the decay time increases exponentially with increasing decay order, with values ranging from 1 ps for a one-phonon process ...

We present a microscopic description of the vibrational spectroscopy of the OH stretch of HOD in liquid D(2)O. Our model predicts that OH frequency correlations decay with a sharp and rapid ( approximately 35 fs) decrease, followed by a beat at approximately 125 fs from intermolecular oxygen vibrations. On a short time scale ( approximately 200 fs), ultrafast infrared spectroscopy of the OH str...