Date of Award

12-2004

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Glen P. Perram, PhD

Abstract

One candidate for the development of a tunable laser in the mid-infrared for use as a defensive countermeasure against passive sensors exploits the nitric oxide (NO) transition at 5.4 μm. However, the difficulty with this mechanism is that when bromine (Br2) and NO are present in a mixture, nitrosyl bromide (BrNO) is also created. The absorption bands present in BrNO complicate the design of such a laser. This thesis determines the forward and reverse rate constants of the reaction of Br2 and NO to form BrNO following the photolysis of BrNO using Fourier Transform Infrared absorption spectroscopy. Other studies have been conducted to determine both the forward and reverse reaction rate constants using different methods, however some of the methods used create uncertainty in the results. In this effort samples with a total pressure of 10.0 torr were used containing either bromine or nitric oxide in excess. The use of Br2 versus NO as the excess reagent has an effect on which mechanism can be used to describe the reaction, but does not affect the reaction rate constants. When NO is the excess reagent, the reaction obeys pseudo first-order kinetics, where the reverse reaction does not significantly impact the overall reaction. This is not true when Br2 is the excess reagent. In both cases, third-order kinetics accurately describe the Br2 + 2NO ↔ 2BrNO reaction giving a forward reaction rate constant of kf = 1.56 ± 0.20 x 10-38 cm6/molecule2- s at 293 ± 1 K. The reverse rate constant was calculated as kr = 2.29 ± 0.33 x 10-21 cm3/molecules and the equilibrium constant as Keq = 171 ± 13 atm-1. This result is consistent with previous results.

AFIT Designator

AFIT-GAP-ENP-04-07

DTIC Accession Number

ADA431081

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