Collisional Quenching of Vibrationally Excited CO in Non-LTE Environment
Author:
Jordan Polvere (Graduate Student)Co-Authors:
Faculty Mentor(s):
Karen Castle, ChemistryFunding Source:
NASA GrantAbstract
The atmosphere of Saturn’s largest moon, Titan, is of growing interest to the space science community. However, since its atmosphere is not in local thermodynamic equilibrium (non-LTE), modeling it requires a deep understanding of the natural excitation and relaxation processes that occur there. Our group has studied CO, the primary reservoir of oxygen on Titan, and its rate of collisional quenching, to contribute toward improving atmospheric models. Using transient diode laser spectroscopy, a quenching rate can be elucidated to significantly higher precision than previously documented in literature. Our experimental procedure begins by flowing small amounts of CO, O3 and Ar through a 1 meter vacuum cell, and firing a 266 nm laser through the cell. O3 absorbs this wavelength and causes the mixture to undergo a temperature jump, allowing some amount of the CO to be excited to higher vibrational states. A mid-IR range diode laser is used to constantly measure the population of CO in a certain state, allowing us to determine the rate of change of the population in a state of interest as it collides with other molecules and is quenched. In this project we are exploring the effects of bath gas identity on CO energy transfer measurements. Specifically, we are investigating the effectiveness of Ar vs. Xe in quenching excited photofragments from the ozone photolysis initiating the temperature-jump. The most recent results of our work will be presented.