Experimental and Theoretical Explorations of Anion Photoelectron Spectroscopy and Photoionization

Anion Photoelectron Spectroscopy;Photoionization;Chemistry

Marquez, Sara AnneBowen, Kit ;

Johns Hopkins University

关键词: Anion Photoelectron Spectroscopy;    Photoionization;    Chemistry;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60090/MARQUEZ-DISSERTATION-2018.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Negatively charged ions were investigated in the gas phase using anion photoelectron spectroscopy. These experiments were conducted using a unique time-of-flight (TOF) mass spectrometer coupled with a magnetic bottle photoelectron spectrometer (PES). The apparatus was fitted with an additional ion source, a novel electrostrpay ionization (ESI) source, leading to necessary modifications to the vacuum system, TOF spectrometer region, and the light baffles. The ESI source generates intact ions in the gas phase from nonvolatile, liquid samples. Since the ESI source is inherently continuous, it must be integrated into the pulsed environment of the TOF mass spectrometer and magnetic bottle PES. A 3D Paul trap was utilized for this purpose, which stores the ions for a variable amount of time before extraction, significantly improving the duty cycle. Mounting the ion trap to the cold head of a liquid nitrogen cooled cryostat creates cold ions resulting in better resolved photoelectron spectra due to the elimination of vibrational hot bands. Furthermore, the low energy photoionization spectrum of propyne was simulated, revealing the consequences of the Jahn-Teller effect and the spin-orbit interaction. Experimental photoionization studies reporting the spectrum of the propyne cation have been published, though there are discrepancies in the conclusions. Such discrepancies are addressed and resolved.