Thesis Veronika Barinkova.pdf (6.77 MB)
Photoejection of molecules from the surface of a liquid microjet
thesis
posted on 2010-05-17, 11:27 authored by Veronika BarinkovaA new instrument has been constructed for studying the dynamics of photochemical
reactions at or near the surface of a liquid. In this apparatus, a liquid microjet is used to deliver
a fresh and continuously flowing liquid surface into a high vacuum chamber. This system has
been coupled with a laser pump-probe to produce and detect radicals. By using laser-induced
fluorescence (LIF) spectroscopy, both the velocity distribution and the population of internal
quantum states in the ejected molecules can be determined.
Designing and building the apparatus required considerable attention with several
significant adjustments being implemented to allow its operation. For instance, a series of
traps were required to attain a vacuum in the low 10-5 mbar range. Using Fraunhofer
diffraction the stability of the microjet has been demonstrated and the diameter has been
confirmed to be 20 µm.
To test the pump-probe procedure, a continuous microjet of a toluene/ethanol mixture has
been subjected to laser photo-ejection using nanosecond pulses of 266 nm laser light. The
time-of-flight distribution of toluene molecules ejected into the gas phase has been measured
using time-resolved LIF spectroscopy. The velocity measurement indicated that the laser photejection
process generated two groups of ejected molecules: (i) a collection of hyperthermal
toluene molecules, which are assumed to be derived from molecules originally at or near the
liquid surface and (ii) a group of slower, hotter molecules that most likely emanate from the
liquid interior.
Concise studies of the other liquid system namely aniline, benzene and acetyl acetone has
also been made and are discussed in this thesis.
History
Supervisor(s)
Ellis, A.Date of award
2010-03-24Awarding institution
University of LeicesterQualification level
- Doctoral
Qualification name
- PhD