Relaxation dynamics of photoexcited cluster ions studied by ion imaging

概要

博 士 論 文

Relaxation dynamics of photoexcited cluster ions
studied by ion imaging
（光励起されたクラスターイオンの画像観測による緩和ダイナミクスの研究）

伊 藤

悠 吏

令和 4 年

Table of contents
Chapter 1. Introduction ················································································ 5
1.1. Relaxation processes of excited molecules and clusters ······························ 5
1.2. Photodissociation dynamics ··································································· 5
1.3. Photofragment imaging technique ··························································· 7
1.4. Photofragment imaging for mass-selected ions ·········································· 8
1.5. Purpose of the present study································································ 12
References ···························································································· 14
Chapter 2. Experimental principles and methods ·········································· 19
2.1. Cluster ion sources ············································································ 19
2.1.1. Laser vaporization ········································································ 19
2.1.2. Electron impact ionization ······························································ 19
2.1.3. Supersonic jet expansion ······························································· 20
2.2. Time-of-flight mass spectrometry ·························································· 20
2.2.1. Principles of time-of-flight mass spectrometry····································· 20
2.2.2. Mass resolution ··········································································· 21
2.2.3. Wiley-McLaren time-of-flight mass spectrometer ································· 22
2.2.4. Reflectron time-of-flight mass spectrometer ······································· 23
2.3. Photofragment ion imaging ·································································· 24
2.3.1. Principles of photofragment ion imaging ············································ 25
2.3.2. Position sensitive detector······························································ 26
2.3.3. Velocity map imaging ···································································· 27
2.4. Product recoil distribution in photodissociation ········································· 28
2.4.1. Image reconstruction methods ························································ 28
2.4.2. Velocity distribution ······································································· 30
2.4.3. Angular distribution ······································································· 31
2.4.4. Anisotropy parameter ···································································· 32
2.5. Experimental setup ············································································ 34
2.5.1. Arrangement of vacuum chambers ·················································· 34

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2.5.2. Details of a linear-type double reflectron imaging apparatus ·················· 35
2.5.3. Image acquisition and analysis························································ 37
2.5.4. Lists of devices and reagents·························································· 38
2.6. Ion trajectory simulation ······································································ 41
2.6.1. Focusing condition in the 2nd reflectron ············································ 41
2.6.2. Calibration curves for fragment recoil velocity····································· 42
References ···························································································· 43
Chapter 3. Visible photodissociation of (NO)2+ ·············································· 45
3.1. Backgrounds ···················································································· 45
3.1.1. Previous studies of NO-containing cluster cations ······························· 45
3.1.2. This study ··················································································· 45
3.2. Methods ·························································································· 46
3.2.1. Experimental methods··································································· 46
3.2.2. Theoretical methods ····································································· 46
3.3. Results and discussion ······································································· 47
3.3.1. Ion imaging results ······································································· 47
3.3.2. Theoretical results ········································································ 49
3.3.3. Translational energy vs. photon energy ············································· 51
3.3.4. Anisotropy parameter vs. photon energy ··········································· 53
3.4. Summary ························································································· 56
3.5. Appendix ·························································································· 57
References ···························································································· 60
Chapter 4. Ultraviolet photodissociation of Mg+-NO ······································ 63
4.1. Backgrounds ···················································································· 63
4.1.1. Previous studies of Mg+-containing cluster ions ·································· 63
4.1.2. This study ··················································································· 64
4.2. Methods ·························································································· 64
4.2.1. Experimental methods··································································· 64
4.2.2. Theoretical methods ····································································· 65

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4.3. Results and discussion ······································································· 65
4.3.1. Ion imaging results ······································································· 65
4.3.2. Theoretical results ········································································ 67
4.3.3. The NO+ channel ········································································· 70
4.3.4. The Mg+ channel ·········································································· 71
4.4. Summary ························································································· 75
4.5. Appendix·························································································· 77
References ···························································································· 79
Chapter 5. Improvement of image resolution ················································ 83
5.1. Backgrounds ···················································································· 83
5.1.1. Problems in the reflectron-type imaging apparatus ······························ 83
5.1.2. Previous studies of variants of imaging electrodes ······························ 84
5.1.3. This study ··················································································· 84
5.2. Methods ·························································································· 85
5.2.1. Design of the new reflectron electrodes ············································ 85
5.2.2. Simulation conditions ···································································· 86
5.2.3. Experimental methods··································································· 86
5.3. Results and discussion ······································································· 87
5.3.1. Simulation results ········································································· 87
5.3.2. Experimental results ····································································· 89
5.3.3. Comparison with the other groups ··················································· 91
5.4. Summary ························································································· 94
5.5. Appendix ·························································································· 95
References ···························································································· 97
Chapter 6. Infrared photodissociation of H+(H2O)1,2-Ar ··································· 99
6.1. Backgrounds ···················································································· 99
6.1.1. Previous studies of gas phase infrared photodissociation ····················· 99
6.1.2. This study ··················································································100
6.2. Experimental methods ·······································································100

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6.3. Results and discussion ······································································101
6.3.1. Infrared photodissociation spectra ··················································101
6.3.2. Ion imaging results ······································································103
6.3.3. Dissociation mechanism of H3O+-Ar ················································106
6.3.4. Dissociation mechanism of H+(H2O)2-Ar ···········································108
6.4. Summary ························································································ 110
6.5. Appendix ························································································· 112
References ··························································································· 116
Chapter 7. ...