Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case...

Electron capture dissociation (ECD) of doubly protonated hyperbranched polyesteramide oligomers (1100-1900 Da) was examined and compared with the structural information obtained by low energy collisionally activated dissociation (CAD). Both the ester and amide bonds of the protonated species were cleaved easily upon ECD with the formation of odd electron (OE(.+)) or even electron (EE(+)) fragme...

This study investigates two features of interest in recent work on the photolytic production of the methoxy carbonyl radical and its subsequent unimolecular dissociation channels. Earlier studies used methyl chloroformate as a photolytic precursor for the CH3OCO, methoxy carbonyl (or methoxy formyl) radical, which is an intermediate in many reactions that are relevant to combustion and atmosphe...

An improved density matrix functional [correction to Buijse and Baerends functional (BBC)] is proposed, in which a hierarchy of physically motivated repulsive corrections is employed to the strongly overbinding functional of Buijse and Baerends (BB). The first correction C1 restores the repulsive exchange-correlation (xc) interaction between electrons in weakly occupied natural orbitals (NOs) a...

A linear relationship was found between the singlet–triplet excitation energy and the energy difference presented by the Kohn–Sham frontier molecular orbitals, independently of the used exchange-correlation functional and of the basis set functions quality. The relationship was explored in three different situations: (a) when the number of carbons is increased in an all-trans acetylene family; ...

High-level ab initio calculations employing the CCSD and CCSD(T) coupled cluster methods with a series of systematically convergent correlation-consistent basis sets have been performed to obtain accurate molecular geometry and energetic properties of the simplest S-nitrosothiol (RSNO), HSNO. The properties of the S-N bond, which are central to the physiological role of RSNOs in the storage and...

Many biomolecular bonds exhibit a mechanical strength that increases in proportion to the logarithm of the rate of force application. Consistent with exponential decrease in bond lifetime under rising force, this kinetically limited failure reflects dissociation along a single thermodynamic pathway impeded by a sharp free energy barrier. Using a sensitive force probe to test the leukocyte adhes...

Recently experiments showed that some adhesive receptor-ligand complexes increase their lifetimes when they are stretched by mechanical force, while the force increase beyond some thresholds their lifetimes decrease. Several specific chemical kinetic models have been developed to explain the intriguing transitions from the “catch-bonds” to the “slip-bonds”. In this work we suggest that the coun...

H(D) atom photofragment translational spectroscopy has been used in a detailed study of the near-UV photolysis of methylamine and its deuteriated analogues at a number of wavelengths in the range 203.0-236.2 nm. Analysis of the total kinetic energy release spectra so obtained serves to reinforce recent suggestions that at least two dissociation pathways lead to H(D) atom fragments. One, 'direct...