Physical Sciences and Mathematics Commons^™

Experimental Study On The Production Of Negative Ion Copper Clusters And Applications, Ran Chu

Masters Theses

At the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratories (ORNL), we investigated the formation, production and potential application of negative-ion copper clusters using mass distributions of negative-ion copper clusters obtained by bombarding various copper samples with Cs ions. The Cu samples – in very large mass-selected clusters Cu (e.g. n=54) – included natural Cu, isotopically enriched copper-63 and copper-65, and electroformed ultra-clean Cu. Mass spectra of negative copper cluster produced by Cs sputter source size up to 50 are shown for the first time.

Three main features were observed for all four copper samples: the intensity …

Strontium Monoxide Measurements In Methane-Air Flames, Bobby J. Wimberly

Masters Theses

The spectroscopy of alkaline earth metal compounds has been an area of active research for several decades. This is at least in part stimulated by the application of these compounds to practical areas ranging from technology to medicine. The use of these compounds in the field of pyrotechnics was the motivation for a series of flame emission spectroscopy (FES) experiments with strontium containing compounds. Specifically, strontium monoxide (SrO) is studied as a candidate radiator for the diagnostic of methane-air flames.

SrO emissions have been observed in flames with temperatures in the range of 1200-1600-K for two compounds: strontium hydroxide and …

Diatomic Carbon Measurements With Laser-Induced Breakdown Spectroscopy, Michael Jonathan Witte

Masters Theses

In this thesis, investigation of well-known carbon Swan spectra is of primary interest. Combustion processes and/or explosion of hydrocarbon fuels cause occurrence of the Swan band system that originates from diatomic carbon. Physical characteristics of low-temperature stars and the interstellar medium can also reveal the Swan bands. The diatomic carbon molecule shows that its lowest rotational levels are sensitive to temperature variation, and higher rotational levels are sensitive to the surrounding gas density and the radiation field. In addition, carbon is a crucial element for life and is the 4th most abundant element; therefore, it is important to ascertain accurately …

Laser-Induced Breakdown Spectroscopy For Analysis Of High Density Methane-Oxygen Mixtures, Matthew Dackman

Masters Theses

The applicability of laser-induced breakdown spectroscopy (LIBS) toward greater than atmospheric density combustion diagnostics is examined. Specifically, this involves ascertaining the feasibility of measuring chemical equivalence ratios directly from atomic emission spectra at high density. The need for such measurement arises from the desire to quantify real time, localized combustion performance in weakly mixed flows. Insufficiently mixed flows generally result in unwanted byproducts, possess the propensity for overall combustion instability, and are increasingly likely to experience localized flame extinction.

We simulate methane/oxygen combustion in ambient pressures ranging 1 to 4 atmospheres, demonstrating these results to be analogous to what would …

Aluminum Monoxide Emission Measurements Following Laser-Induced Breakdown For Plasma Characterization, David Michael Surmick

Masters Theses

In this work, spectroscopic emissions from laser ablated aluminum samples are used to characterize the time dependent decay of laser-induced plasma. The plasma is created by tightly focusing nanosecond pulsed laser radiation. Time resolved measurements of the plasma are made with a gated, intensified linear diode array coupled to an optical multichannel analyzer and/or an intensified charged coupled device. Time resolution is achieved by synchronizing the laser with the measurement rate of the array detector.

Computed diatomic molecular aluminum monoxide emissions were used to infer the temperature of the plasma as a function of time. This was completed by comparing …

Radiation-Induced Radicals In Polyurea-Crosslinked Silica Aerogel, Benjamin Michael Walters

Masters Theses

Free radicals are atoms or molecules with an odd number of electrons in an outer shell. Since electrons typically occur in pairs, this leaves one electron that is unpaired. In seek of another electron to pair with, free radicals react with and steal electrons from neighboring molecules, which then become free radicals themselves. This can start a chain reaction, cascading into large scale damage.

Ionizing radiation can tear through molecules, just as bullets can tear through things that we see. If free radicals can be detected, and seen to increase in a material upon radiation exposure, this can indicate molecular …