氣膠乃懸浮於氣體中極精微粒子之泛稱。氣膠在許多重要研究領域包括環境化學、大氣化學、星際化學乃至全球氣候變遷中所扮演的關鍵性角色已被學界所認知。然而由於氣膠本身的組成、尺寸、內部結構以及外在型態皆相當多元化，怎麼樣從原子及分子層級了解氣膠本身物理、化學、光學等基礎性質進而影響周遭環境、大氣結構乃至氣候變遷就顯得很重要。為了能夠深入探討這個重要卻迫切待解決的議題，我們正建置一套新一代多功能氣膠探測儀。這套多功能氣膠探測儀，能夠針對氣膠奈米粒子之能級(包括電子能級及振動能級)、結構特性、生成機制及動態學加以探究。此多功能氣膠探測儀由三大部分構成 : (1)傅立葉轉換紅外光譜耦合之氣膠腔體(aerosol chamber)，(2)可調式氣動聚焦系統(adjustable aerodynamic lens system)，其可選擇粒徑大小及聚焦形成粒子束以及(3)紫外光光電子能譜腔體(photoelectron spectrometer chamber)。氣膠粒子可經由霧化器產生並引導至氣膠腔體內進行紅外光譜偵測，或是藉由精確控制氣膠腔體的溫度及壓力使氣膠的組成分子直接在氣膠腔體中形成聚集(aggregate)。氣膠粒子的尺寸分布及濃度可由掃描式粒徑分析系統(scanning mobility particle sizer, SMPS) 得知。整體實驗設備的建構已初步完成，而內容將會對此多功能氣膠探測儀各個部分的初步測試結果做討論及探討。

“Aerosols”, suspensions of ultrafine particulates in a gas, play significant roles
in a number of important research fields, including the atmospheric chemistry, planetary sciences, environmental sciences as well as the biomedical sciences and therapeutic administration. Since aerosols have various size, shape, composition and architecture, it is crucial to understand the fundamental physical, chemical and optical properties of aerosols from the atomic and molecular level. In order to address these issues, we have recently constructed a novel multi-functional aerosol instrument. This new multi-functional aerosol instrument is composed of three main parts, including (I) a long- path, temperature adjustable aerosol chamber coupled with the rapid-scan Fourier transform infrared spectrometer, (II) an adjustable aerodynamic lens system to produce a focused and size-selected aerosol particle beam, and (III) an aerosol ultraviolet photoelectron spectrometer (UPS) chamber with a high-resolution hemispherical electron energy analyzer. Aerosols are generated either by an atomizer or formed in-situ in the long-path aerosol chamber under well-controlled conditions. The aerosol size distribution and concentration are characterized via a scanning mobility particle sizer (SMPS). The performance of this newly developed aerosol instrument and some preliminary results of each part will be discussed.

Chapter 1 Introduction……………………………………………………………..1
1.1 The significance of aerosols…………………………………………...3
1.1.1 Atmospheric chemistry……………………………………….....4
1.1.2 Environment sciences…………………………………………...6
1.1.3 Biomedical chemistry…………………………………………...7
1.2 Conventional techniques for aerosol measurements………………….7
1.2.1 Aerosol mass spectrometry (AMS)……………………………..8
1.2.2 Optical measurement techniques……………………………......9
1.3 Challenges in characterizing aerosols………………………………...10
1.4 Issues of interest………………………………………………………11
Chapter 2 Experimental setup and aerosol preparation………..……………….13
2.1 Overview of the instrument…………………………………………...13
2.2 Aerosol generation ……………………………………………….…...14
2.3 Water removal by Nafion dryer…………………………………….…17
2.3.1 Structure and physical properties of Nafion…………………….17
2.3.2 Advantages of Nafion dryer over other dryers……………….…19
2.3.3 Nafion dryer working mechanism…………………………….21
2.3.4 Temperature effect…………………………………………….22
2.4 Scanning mobility particle sizer (SMPS)…………………………...23
2.4.1 Differential mobility analyzer (DMA)………………………..25
2.4.2 Condensation particle counter (CPC)…………………………28
2.4.3 Size distribution of aerosols…………………………………..30
Chapter 3 Long path aerosol cooling chamber coupled with time-resolved Fourier transform infrared spectrometer (FTIR)…………………34
3.1 Fourier transform infrared spectrometer……………………………34
3.2 Infrared spectroscopy of aerosols…………………………………..36
3.3 Long-path aerosol cooling chamber………………………………...38
3.3.1 Variable long-path cell………………………………………...39
3.3.2 Well-defined environment conditions………………………...41
3.3.3 In-situ investigation via rapid scan time-resolved FTIR………41
Chapter 4 Vibrational spectroscopy of aerosols from the long-path aerosol cooling chamber………………………………………………………43
4.1 Water aerosols……………………………………………………….43
4.1.1 Ice structure……………………………………………………45
4.1.2 Temperature effect……………………………………….……47
4.1.3 Buffer gas pressure effect…………………………….……….50
4.2.3 Time evolution of water aerosols………………………….….52
4.2 Ammonium sulfate aerosols…………………………………….…..57
4.2.1 Introduction…………………………………………….……..57
4.2.2 Vibrational spectroscopic features of ammonium sulfate-water mixed droplets at room temperature……………………….…59
4.2.3 Effect of water on the ammonium sulfate aerosols…………...60
4.2.4 Time evolution of ammonium sulfate-water mixed aerosols....63
4.3 Protein aerosols……………………………………………………..71
4.4 Cysteine-water mixed aerosols………………………………….…..74
Chapter 5 Adjustable aerodynamic lens (ADL) system………………………..78
5.1 ADL introduction……………………………………………………78
5.2 ADL components……………………………………………………80
5.3 Functions of ADL system……………………………………………81
5.4 Simulation of aerodynamic lens for optimal design…………………82
5.4.1 Simulation software……………………………………………82
5.4.2 Optimal ADL design for aerosols of various size range…….….84
5.4.3 Characterization of the collimated aerosol beam formed via ADL system…………………………………………………….….…86
Chapter 6 Aerosol ultraviolet photoelectron spectroscopy (UPS)……….….…..87
6.1 Photoelectron spectroscopy……………………………………..…….87
6.2 Photoelectron spectroscopy of suspended droplets and nanoparticles..89
6.3 The advantages of UPS………………………………………….……94
6.4 Aerosol ultraviolet photoelectron spectroscopy setup………………..95
6.5 Ionization light sources…………………………………………….…98
6.5.1 Incoherent UV lamp………………………………………….…98
6.5.2 Options of light sources………………..…………………….…100
6.6 Hemispherical electron energy analyzer……………………………...101
6.7 Preliminary tests on aerosol UPS…………………………………….105
6.7.1 Effusive Ar gas…………………………………………………105
6.7.2 Effusive N2 gas………………………………………………... 106
6.8 Perspective and future plans…………………………………………108
Chapter 7 Conclusions…………………………………………………………….109
References…………………………………………………………………………….111

1. Nash, D. G.; Baer, T.; Johnston, M. V., Aerosol mass spectrometry: An introductory review. International Journal of Mass Spectrometry 2006, 258 (1–3), 2-12.
2. Canagaratna, M. R.; Jayne, J. T.; Jimenez, J. L.; Allan, J. D.; Alfarra, M. R.; Zhang, Q.; Onasch, T. B.; Drewnick, F.; Coe, H.; Middlebrook, A.; Delia, A.; Williams, L. R.; Trimborn, A. M.; Northway, M. J.; DeCarlo, P. F.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R., Chemical and microphysical characterization of ambient aerosols with the aerodyne aerosol mass spectrometer. Mass Spectrometry Reviews 2007, 26 (2), 185-222.
3. Hinz, K.-P.; Spengler, B., Instrumentation, data evaluation and quantification in on-line aerosol mass spectrometry. Journal of Mass Spectrometry 2007, 42 (7), 843-860.
4. Murphy, D. M., The design of single particle laser mass spectrometers. Mass Spectrometry Reviews 2007, 26 (2), 150-165.
5. Hinds, W.; Reist, P. C., Aerosol measurement by laser doppler spectroscopy—I. Theory and experimental results for aerosols homogeneous. Journal of Aerosol Science 1972, 3 (6), 501-514.
6. King, G. B.; Sorensen, C. M.; Lester, T. W.; Merklin, J. F., Photon correlation spectroscopy used as a particle size diagnostic in sooting flames. Appl. Opt. 1982, 21 (6), 976_1.
7. Flower, W. L., Optical Measurements of Soot Formation in Premixed Flames. Combustion Science and Technology 1983, 33 (1-4), 17-33.
8. Sigurbjörnsson, Ó. F.; Firanescu, G.; Signorell, R., Intrinsic Particle Properties from Vibrational Spectra of Aerosols. Annual Review of Physical Chemistry 2009, 60 (1), 127-146.
9. Firanescu, G.; Hermsdorf, D.; Ueberschaer, R.; Signorell, R., Large molecular aggregates: from atmospheric aerosols to drug nanoparticles. Physical Chemistry Chemical Physics 2006, 8 (36), 4149-4165.
10. Preston, T. C.; Wang, C. C.; Signorell, R., Infrared spectroscopy and modeling of co-crystalline CO[sub 2] [center-dot] C[sub 2]H[sub 2] aerosol particles. I. The formation and decomposition of co-crystalline CO[sub 2] [center-dot] C[sub 2]H[sub 2] aerosol particles. The Journal of Chemical Physics 2012, 136 (9), 094509-9.

11. Wang, C. C.; Zielke, P.; Sigurbjörnsson, O. m. F.; Viteri, C. R.; Signorell, R., Infrared Spectra of C2H6, C2H4, C2H2, and CO2 Aerosols Potentially Formed in Titan’s Atmosphere†. The Journal of Physical Chemistry A 2009, 113 (42), 11129-11137.
12. Bauerecker, S.; Taraschewski, M.; Weitkamp, C.; Cammenga, H. K., Liquid-helium temperature long-path infrared spectroscopy of molecular clusters and supercooled molecules. Review of Scientific Instruments 2001, 72 (10), 3946-3955.
13. Sigurbjornsson, O. F.; Signorell, R., Evidence for the existence of supercooled ethane droplets under conditions prevalent in Titan's atmosphere. Physical Chemistry Chemical Physics 2008, 10 (41), 6211-6214.
14. Lang, E. K.; Knox, K. J.; Wang, C. C.; Signorell, R., The influence of methane, acetylene and carbon dioxide on the crystallization of supercooled ethane droplets in Titan's clouds. Planetary and Space Science 2011, 59 (8), 722-732.
15. Najera, J. J.; Fochesatto, J. G.; Last, D. J.; Percival, C. J.; Horn, A. B., Infrared spectroscopic methods for the study of aerosol particles using White cell optics: Development and characterization of a new aerosol flow tube. Review of Scientific Instruments 2008, 79 (12), 124102-12.
16. Bauerecker, S.; Wargenau, A.; Schultze, M.; Kessler, T.; Tuckermann, R.; Reichardt, J., Observation of a transition in the water-nanoparticle formation process at 167 K. The Journal of Chemical Physics 2007, 126 (13), 134711-6.
17. Medcraft, C.; McNaughton, D.; Thompson, C. D.; Appadoo, D. R. T.; Bauerecker, S.; Robertson, E. G., Water ice nanoparticles: size and temperature effects on the mid-infrared spectrum. Physical Chemistry Chemical Physics 2013, 15 (10), 3630-3639.
18. Devlin, J. P.; Joyce, C.; Buch, V., Infrared Spectra and Structures of Large Water Clusters. The Journal of Physical Chemistry A 2000, 104 (10), 1974-1977.
19. Devlin, J. P.; Sadlej, J.; Buch, V., Infrared Spectra of Large H2O Clusters:  New Understanding of the Elusive Bending Mode of Ice. The Journal of Physical Chemistry A 2001, 105 (6), 974-983.
20. Clapp, M. L.; Worsnop, D. R.; Miller, R. E., Frequency-dependent optical constants of water ice obtained directly from aerosol extinction spectra. The Journal of Physical Chemistry 1995, 99 (17), 6317-6326.
21. Murphy, D. M., Dehydration in cold clouds is enhanced by a transition from cubic to hexagonal ice. Geophysical Research Letters 2003, 30 (23), 2230.

22. Johnston, J. C.; Molinero, V., Crystallization, Melting, and Structure of Water Nanoparticles at Atmospherically Relevant Temperatures. Journal of the American Chemical Society 2012, 134 (15), 6650-6659.
23. Murray, B. J.; Knopf, D. A.; Bertram, A. K., The formation of cubic ice under conditions relevant to Earth's atmosphere. Nature 2005, 434 (7030), 202-205.
24. Wise, M. E.; Baustian, K. J.; Tolbert, M. A., Internally mixed sulfate and organic particles as potential ice nuclei in the tropical tropopause region. Proceedings of the National Academy of Sciences 2010, 107 (15), 6693-6698.
25. Jensen, E. J.; Pfister, L.; Bui, T. P.; Lawson, P.; Baumgardner, D., Ice nucleation and cloud microphysical properties in tropical tropopause layer cirrus. Atmos. Chem. Phys. 2010, 10 (3), 1369-1384.
26. Shilling, J. E.; Fortin, T. J.; Tolbert, M. A., Depositional ice nucleation on crystalline organic and inorganic solids. Journal of Geophysical Research: Atmospheres 2006, 111 (D12), D12204.
27. Abbatt, J. P. D.; Benz, S.; Cziczo, D. J.; Kanji, Z.; Lohmann, U.; Möhler, O., Solid Ammonium Sulfate Aerosols as Ice Nuclei: A Pathway for Cirrus Cloud Formation. Science 2006, 313 (5794), 1770-1773.

28. Cziczo, D. J.; Froyd, K. D.; Hoose, C.; Jensen, E. J.; Diao, M.; Zondlo, M. A.; Smith, J. B.; Twohy, C. H.; Murphy, D. M., Clarifying the Dominant Sources and Mechanisms of Cirrus Cloud Formation. Science 2013, 340 (6138), 1320-1324.
29. Badger, C. L.; George, I.; Griffiths, P. T.; Braban, C. F.; Cox, R. A.; Abbatt, J. P. D., Phase transitions and hygroscopic growth of aerosol particles containing humic acid and mixtures of humic acid and ammonium sulphate. Atmos. Chem. Phys. 2006, 6 (3), 755-768.
30. Segal-Rosenheimer, M.; Dubowski, Y.; Linker, R., Extraction of optical constants from mid-IR spectra of small aerosol particles. Journal of Quantitative Spectroscopy and Radiative Transfer 2009, 110 (6–7), 415-426.
31. Gopalakrishnan, S.; Liu, D.; Allen, H. C.; Kuo, M.; Shultz, M. J., Vibrational Spectroscopic Studies of Aqueous Interfaces:  Salts, Acids, Bases, and Nanodrops. Chemical Reviews 2006, 106 (4), 1155-1175.
32. Kolesov, B. A.; Minkov, V. S.; Boldyreva, E. V.; Drebushchak, T. N., Phase Transitions in the Crystals of l- and dl-Cysteine on Cooling: Intermolecular Hydrogen Bonds Distortions and the Side-Chain Motions of Thiol-Groups. 1. l-Cysteine. The Journal of Physical Chemistry B 2008, 112 (40), 12827-12839.

33. Sarangi, R.; Frank, P.; Benfatto, M.; Morante, S.; Minicozzi, V.; Hedman, B.; Hodgson, K. O., The x-ray absorption spectroscopy model of solvation about sulfur in aqueous L-cysteine. The Journal of Chemical Physics 2012, 137 (20), 205103-13.
34. Liu, P.; Ziemann, P. J.; Kittelson, D. B.; McMurry, P. H., Generating Particle Beams of Controlled Dimensions and Divergence: I. Theory of Particle Motion in Aerodynamic Lenses and Nozzle Expansions. Aerosol Science and Technology 1995, 22 (3), 293-313.
35. Liu, P.; Ziemann, P. J.; Kittelson, D. B.; McMurry, P. H., Generating Particle Beams of Controlled Dimensions and Divergence: II. Experimental Evaluation of Particle Motion in Aerodynamic Lenses and Nozzle Expansions. Aerosol Science and Technology 1995, 22 (3), 314-324.
36. Zhang, X.; Smith, K. A.; Worsnop, D. R.; Jimenez, J.; Jayne, J. T.; Kolb, C. E., A Numerical Characterization of Particle Beam Collimation by an Aerodynamic Lens-Nozzle System: Part I. An Individual Lens or Nozzle. Aerosol Science and Technology 2002, 36 (5), 617-631.
37. Zhang, X.; Smith, K. A.; Worsnop, D. R.; Jimenez, J. L.; Jayne, J. T.; Kolb, C. E.; Morris, J.; Davidovits, P., Numerical Characterization of Particle Beam Collimation: Part II Integrated Aerodynamic-Lens–Nozzle System. Aerosol Science and Technology 2004, 38 (6), 619-638.
38. Jayne, J. T.; Leard, D. C.; Zhang, X.; Davidovits, P.; Smith, K. A.; Kolb, C. E.; Worsnop, D. R., Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Submicron Particles. Aerosol Science and Technology 2000, 33 (1-2), 49-70.
39. Northway, M. J.; Jayne, J. T.; Toohey, D. W.; Canagaratna, M. R.; Trimborn, A.; Akiyama, K. I.; Shimono, A.; Jimenez, J. L.; DeCarlo, P. F.; Wilson, K. R.; Worsnop, D. R., Demonstration of a VUV Lamp Photoionization Source for Improved Organic Speciation in an Aerosol Mass Spectrometer. Aerosol Science and Technology 2007, 41 (9), 828-839.
40. Gao, S.; Zhang, Y.; Meng, J.; Shu, J., Online investigations on ozonation products of pyrene and benz[a]anthracene particles with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer. Atmospheric Environment 2009, 43 (21), 3319-3325.
41. Shu, J.; Gao, S.; Li, Y., A VUV Photoionization Aerosol Time-of-Flight Mass Spectrometer with a RF-Powered VUV Lamp for Laboratory-Based Organic Aerosol Measurements. Aerosol Science and Technology 2008, 42 (2), 110-113.
42. Loh, N. D.; Hampton, C. Y.; Martin, A. V.; Starodub, D.; Sierra, R. G.; Barty, A.; Aquila, A.; Schulz, J.; Lomb, L.; Steinbrener, J.; Shoeman, R. L.; Kassemeyer, S.; Bostedt, C.; Bozek, J.; Epp, S. W.; Erk, B.; Hartmann, R.; Rolles, D.; Rudenko, A.; Rudek, B.; Foucar, L.; Kimmel, N.; Weidenspointner, G.; Hauser, G.; Holl, P.; Pedersoli, E.; Liang, M.; Hunter, M. M.; Gumprecht, L.; Coppola, N.; Wunderer, C.; Graafsma, H.; Maia, F. R. N. C.; Ekeberg, T.; Hantke, M.; Fleckenstein, H.; Hirsemann, H.; Nass, K.; White, T. A.; Tobias, H. J.; Farquar, G. R.; Benner, W. H.; Hau-Riege, S. P.; Reich, C.; Hartmann, A.; Soltau, H.; Marchesini, S.; Bajt, S.; Barthelmess, M.; Bucksbaum, P.; Hodgson, K. O.; Struder, L.; Ullrich, J.; Frank, M.; Schlichting, I.; Chapman, H. N.; Bogan, M. J., Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight. Nature 2012, 486 (7404), 513-517.
43. Wang, X.; McMurry, P. H., Instruction Manual for the Aerodynamic Lens Calculator. Aerosol Science and Technology 2006, 40 (5), 1-10.
44. Peterka, D. S.; Kim, J. H.; Wang, C. C.; Poisson, L.; Neumark, D. M., Photoionization Dynamics in Pure Helium Droplets†. The Journal of Physical Chemistry A 2007, 111 (31), 7449-7459.
45. Wang, C. C.; Kornilov, O.; Gessner, O.; Kim, J. H.; Peterka, D. S.; Neumark, D. M., Photoelectron Imaging of Helium Droplets Doped with Xe and Kr Atoms†. The Journal of Physical Chemistry A 2008, 112 (39), 9356-9365.
46. Kornilov, O.; Wang, C. C.; Bünermann, O.; Healy, A. T.; Leonard, M.; Peng, C.; Leone, S. R.; Neumark, D. M.; Gessner, O., Ultrafast Dynamics in Helium Nanodroplets Probed by Femtosecond Time-Resolved EUV Photoelectron Imaging†. The Journal of Physical Chemistry A 2009, 114 (3), 1437-1445.
47. Kornilov, O.; Bünermann, O.; Haxton, D. J.; Leone, S. R.; Neumark, D. M.; Gessner, O., Femtosecond Photoelectron Imaging of Transient Electronic States and Rydberg Atom Emission from Electronically Excited He Droplets. The Journal of Physical Chemistry A 2011, 115 (27), 7891-7900.
48. Shu, J.; Wilson, K. R.; Ahmed, M.; Leone, S. R., Coupling a versatile aerosol apparatus to a synchrotron: Vacuum ultraviolet light scattering, photoelectron imaging, and fragment free mass spectrometry. Review of Scientific Instruments 2006, 77 (4), 043106.
49. Wilson, K. R.; Peterka, D. S.; Jimenez-Cruz, M.; Leone, S. R.; Ahmed, M., VUV photoelectron imaging of biological nanoparticles: Ionization energy determination of nanophase glycine and phenylalanine-glycine-glycine. Physical Chemistry Chemical Physics 2006, 8 (16), 1884-1890.
50. Wilson, K. R.; Zou, S.; Shu, J.; Rühl, E.; Leone, S. R.; Schatz, G. C.; Ahmed, M., Size-Dependent Angular Distributions of Low-Energy Photoelectrons Emitted from NaCl Nanoparticles. Nano Letters 2007, 7 (7), 2014-2019.
51. Yoder, B. L.; West, A. H. C.; Schlappi, B.; Chasovskikh, E.; Signorell, R., A velocity map imaging photoelectron spectrometer for the study of ultrafine aerosols with a table-top VUV laser and Na-doping for particle sizing applied to dimethyl ether condensation. The Journal of Chemical Physics 2013, 138 (4), 044202-12.
52. Ottosson, N.; Børve, K. J.; Spångberg, D.; Bergersen, H.; Sæthre, L. J.; Faubel, M.; Pokapanich, W.; Öhrwall, G.; Björneholm, O.; Winter, B., On the Origins of Core−Electron Chemical Shifts of Small Biomolecules in Aqueous Solution: Insights from Photoemission and ab Initio Calculations of Glycineaq. Journal of the American Chemical Society 2011, 133 (9), 3120-3130.
53. Pluhařová, E.; Ončák, M.; Seidel, R.; Schroeder, C.; Schroeder, W.; Winter, B.; Bradforth, S. E.; Jungwirth, P.; Slavíček, P., Transforming Anion Instability into Stability: Contrasting Photoionization of Three Protonation Forms of the Phosphate Ion upon Moving into Water. The Journal of Physical Chemistry B 2012, 116 (44), 13254-13264.