Development of an atmospheric pressure ionization source for in situ monitoring of degradation products of atmospherically relevant volatile organic c [...] / submitted by Hendrik Kersten. 2011
Inhalt
- Leerblatt
- Widmung
- Leerblatt
- Danksagung final
- Leerblatt
- Leerblatt
- korr Abstract final
- korr final
- Table of Contents
- Notation and Terminology
- 1 Introduction
- 2 Goals
- 3 Experimental
- 3.1 Mass Spectrometer
- a) Storing mass range capability.
- b) Mass discrimination
- c) Mass analysis
- d) Mass resolution
- e) Mass accuracy
- f) Switching positive-negative modus
- g) Resonant excitation
- h) Ion isolation
- i) CID
- j) Msn experiments
- k) Duty cycle
- l) Chromatogram mode
- m) Software
- 3.1.1 Laser Systems
- 3.1.2 Common API Source
- 3.1.3 Novel Laminar-Flow Ion Source (LFIS)
- 3.1.4 Novel APPI Setup
- 3.1.4.1 Setup for Characterization of Transfer Capillaries
- 3.1.4.2 Characterization of the Discharge Lamp
- 3.1.3 Setup for Neutral Radical Induced ITP Studies [82]
- 3.3 Photoreactor
- 3.3.1 Procedure of Atmospheric Degradation Studies
- 3.3.2 FT-IR-setup
- 3.3.3 MS Sampling Unit
- 3.3.4 MS Ionization Unit
- 3.4 Chemicals
- 3.5 Computational Investigations
- 4 Results and Discussion
- 4.1 Common API sources
- 4.1.1 Distribution of Ion Acceptance (DIA) Studies
- 4.1.2 Fluid Dynamical Behavior
- 4.1.3 H2O and O2 Background Concentrations [82]
- 4.2 Development of a Novel API Approach
- 4.2.1 LFIS - Preliminary Experiments
- a) Rough determination of the flow characteristics
- b) Ion transmission efficiencies
- c) Different behavior of quartz and metal tubes
- d) Impact of the laser frequency in coaxial configuration
- e) Suggestive estimate of coaxial sensitivity
- 4.2.2 LFIS - Realization
- 4.2.3 Development of APPI on Transfer Capillaries
- 4.2.3.1 Characterization of Transfer Capillaries
- a) Comparison of original and home–made capillary
- b) Adaptability of fluid dynamic equations - laminar or turbulent
- c) Critical and static pressure, velocity distribution, and transit times
- d) Upstream pressure variation
- 4.2.3.2 First APPI on Capillary Approach
- 4.2.3.3 Development of Miniature VUV Spark Discharge Lamps
- a) In general
- b) High voltage-power supplies
- c) APPI with or without window
- d) Balanced pressure separation
- e) Lamp design 1
- f) Lamp design 2
- g) Lamp design 3
- h) Operating stability tests
- i) Determination of lower detection limits (LODs)
- j) Experimental sparking characteristics of design 3 with the DD20_10 C-Lader
- k) Theoretical considerations on the spark characteristics
- l) Optical emission spectroscopy (OES)
- m) VUV emission efficiency in comparison to the commercially available APPI lamp
- n) VUV emission spectroscopy below 105 nm
- 4.2.3.4 Impact of Different Ionization Positions on MS Spectra
- 4.3 Ion Transformation Processes (ITP)
- 4.3.1 Unintended Collision Induced ITP
- 4.3.2 Neutral Radical Induced ITP (NRITP) [82]5F
- 4.3.2.1 Evidence for Ion-Neutral Radical Chemistry
- 4.3.2.2 Oxidation of the Pyrene Radical Cation - Feasible Pathways
- 4.3.2.3 Oxidation of the Pyrene Radical Cation - Kinetic Investigations
- a) Impact of O2, O(3P), and O3 on the ion distribution
- b) Impact of H2O, OH, and H on the ion distribution
- c) Impact of Cl, ClO, and ClOO on the ion distribution
- 4.3.2.4 Consequences for Degradation Studies with APPI-MS
- 4.3.3 ITP via Chemical Ionization
- 4.4 Degradation Studies
- 4.4.1 Features and limitations of the MS setup
- 4.4.2 Exemplary Degradation Study
- 5 Summary and Conclusion
- a) Investigations on the commercially available API source
- b) Development of a laminar flow ion source with a laminar sampling unit
- c) Novel APPI approach with home-built miniature spark discharge lamps
- d) Ion transformation processes
- e) Exemplary degradation study of p-xylene
- 6 Indexes