Files in this item

FilesDescriptionFormat

application/vnd.openxmlformats-officedocument.presentationml.presentation

949062.pptx (4MB)
PresentationMicrosoft PowerPoint 2007

application/pdf

2586.pdf (16kB)
AbstractPDF

application/pdf

Insight_into_th ... tituted_MALDI_Matrices.pdf (3MB)
PresentationPDF

Description

 Title: INSIGHT INTO THE CHARGE TRANSFER MECHANISMS OF HEAVY ATOM SUBSTITUTED MALDI MATRICES Author(s): Bridgmohan, Chelsea N Contributor(s): Kirmess, Kristopher M; Wang, Lichang Subject(s): Theory and Computation Abstract: The underlying mechanism of how MALDI matrices work is poorly understood. Experimental literature suggests that the triplet excited state (T$_{1}$) of the matrix plays a significant role in its ability to transfer charge to the analyte effectively. The heavy atom substitution effect predicts that the addition of a heavy atom to an otherwise "dead" matrix, such as 2,4-dihydroxybenzoic acid, would increase the rate of Intersystem Crossing (ISC) to the T$_{1}$ state via spin-orbit coupling. This effect was observed experimentally as there was a visible decay in singlet lifetime and an increase in triplet lifetime, as well as a better matrix performance when compared to its original, unsubstituted partner. To provide insight into the photophysical properties of 2,4-dihydroxybenzoic acid and its halogenated isomers, calculations were performed using \textit{Gaussian09}. Geometry optimizations, frequencies, and IR spectra of all isomers were calculated using Density Functional Theory (DFT) with B3LYP functional and the 6-31G+(d,p) basis set. UV-Vis and fluorescence spectra were generated using Time-Dependent DFT (TDDFT). The following values for the singlet ground state (S$_{0}$), triplet excited state (T$_{1}$), and singlet excited state (S$_{1}$) were tabulated and compared: optimization energies, HOMO-LUMO energies and orbital contours, and bond distances. In addition, the energy values for Proton Affinity (PA) and Gas Phase Acidity (GPA) were determined. Issue Date: 6/21/2017 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/96966 DOI: 10.15278/isms.2017.WI05 Date Available in IDEALS: 2017-07-272018-01-29
﻿