Off-campus UMass Amherst users: To download campus access theses, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users: Please talk to your librarian about requesting this thesis through interlibrary loan.

Theses that have an embargo placed on them will not be available to anyone until the embargo expires.

Document Type

Open Access

Degree Program

Chemistry

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2011

Month Degree Awarded

May

Keywords

Electronic and Vibrational Spectroscopy of Ni+(H2O)

Abstract

The electronic and vibrational spectra of Ni+(H2O) were measured using photofragment spectroscopy. In the electronic spectrum, photodissociation is observed at photon energies above 16875 cm-1. The only fragment observed is Ni+. The electronic spectrum consists of well-resolved peaks spaced by ~340 cm-1, due to a vibrational progression in the excited electronic state. These peaks have complex sub-structure, consisting of a triplet, spaced by ~30 cm-1. The sub-structure is due to rotational structure in a perpendicular transition of a prolate top molecule. In addition to this major progression, there is a series of less intense, single peaks spaced by ~340 cm-1. These may be due to a vibrational progression in a second electronic state, this time due to a parallel transition.

The O-H stretching vibrations of Ni+(H2O) were measured using vibrationally mediated photodissociation (VMP) in a depletion experiment, only monitoring transitions from K’’=1. This revealed a O-H symmetric stretch at 3629 cm-1 and antisymmetric O-H stretch at 3692 cm-1.

Several electronic structure calculations complement the experiments using the BHandHLYP hybrid density functional and the 6-311++G(3dp, f) basis set. At this level of theory, Ni+(H2O) is predicted to have C2v symmetry and 2A1 ground state. The Ni-O bond length is 1.95, the O-H bond lengths are .955 and the H-O-H angle is 108.2˚ The molecule is a near-prolate top, with rotational constants A=13.98 cm-1, B=0.297 cm-1 and C=0.296 cm-1 . Analysis of the electronic and vibrational spectra reveals that binding to Ni+ removes electron density from the oxygen lone pairs, increasing the H-O-H bond angle from its value in bare H2O. The electronic and vibrational spectra corresponds to 4s ¬3d transistion in Ni+. As a result of electronic excitation, the Ni-O bond stretches by .20 Å, and the H-O-H bond angle is reduced.

First Advisor

Ricardo B. Metz

Share

COinS