Acquisition of a laser desorption-time-of-flight mass spectrometry system for measuring ultrafast dissociation dynamics in energetic molecules
Abstract
Understanding the initial dissociation mechanisms of isolated energetic molecules is needed in order to develop novel energetic molecules that possess tailored properties such as high energy density and the ability to be selectively detonated upon optical excitation. The present proposal requests funds for purchase of instrumentation components to construct a femtosecond laser desorption-orthogonal acceleration time-of-flight mass spectrometer that will enable pump-probe measurements of the dissociation dynamics of isolated energetic molecules with unprecedented time resolution of <25 femtoseconds. The requested instrumentation consists of (1) a femtosecond fiber laser for desorption, (2) a custom-built orthogonal acceleration time-of-flight mass spectrometer (oa-RETOF) capable of detecting both positive and negative ions, (3) vacuum-compatible translation stages for sample manipulation, (4) turbomolecular vacuum pumps and accessories to achieve ultrahigh vacuum conditions in the oa-RETOF, and (5) a vibrationally isolated optical table for mounting the above components. These components will be interfaced with an existing commercial Ti:Sapphire femtosecond laser coupled to an optical parametric amplifier (OPA) in the PIÕs laboratory that provides multiple beamlines for pump- probe experiments. Collectively, this instrumentation will create a unified laser desorption time- of-flight mass spectrometry system for investigating the ultrafast dissociation dynamics of energetic molecules. Experiments with femtosecond laser desorption and time-delayed femtosecond pump-probe excitation of the isolated desorbed molecules will be conducted on two groups of energetic molecules: (1) traditional nitro-based high explosives including trinitrotoluene (TNT), 3,5-trinitroperhydro-1,3,5-triazine (RDX), 1,3,5-triamino-2,4,6- trinitrobenzene (TATB) and (2) new high-nitrogen content molecules including 5,5 -bistetrazole (5,5 -BT), 1,5 -bistetrazole (1,5 -BT), and 3,3 -diamino-4,4 -azoxyfurazan (DAAF). Time-resolved desorb-pump-probe experiments will be conducted on these molecules prepared as radical cations, electronically excited neutrals, and radical anions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 18, 2019
- Source ID
- W911NF1910182
Entities
People
- Katharine Moore Tibbetts
Organizations
- Army Contracting Command
- United States Army
- Virginia Commonwealth University