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정보검색

소장정보 검색

국회도서관 홈으로 정보검색 소장정보 검색
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Title Page

Contents

ABSTRACT 10

국문초록 11

CHAPTER 1. INTRODUCTION 12

1.1. Laser Induced breakdown spectroscopy 12

1.1.1. Advantages and Disadvantages of LIBS 15

1.2. Experimental Samples, Heavy metals 16

1.2.1. Copper 17

1.2.2. Zinc 17

1.2.3. Cadmium 18

CHAPTER 2. PRINCIPLES OF LIBS 19

2.1. LIBS Energy Source 19

2.2. Interaction of Laser beam with matter 21

2.2.1. Spectral Emission from Plasma 23

2.2.2. Laser Induced Vaporization 24

2.2.3. Plasma generation 27

2.3. Plasma Temperature 28

2.4. Electron Density 31

2.5. Binding Materials 33

CHAPTER 3. EXPERIMENTAL SETUP 35

3.1. LIBS Experiment 35

3.1.1. Nd:YAG (Minilite II) Laser 35

3.1.2. Optical detection system and Software 36

3.1.3. Experimental Setup 37

3.2. Solid samples and Preparation 39

CHAPTER 4. RESULTS AND DISCUSSION 40

4.1. Parameter optimization of LIBS 40

4.1.1. Q-switch delay, Spot size, Laser irradiance 40

4.1.2. Distance between incident radiation focusing lens and target 42

4.1.3. Distance between incident radiation collective lens and target 43

4.1.4. Sample rotation speed on LIBS signal intensity 44

4.1.5. Repetition rate and LIBS signal intensity 45

4.2. Solid sample 46

4.2.1. Cu foil 46

4.2.2. Zinc foil 51

4.2.3. Excitation temperature 54

4.2.3.1. Line pair intensity ratio method 54

4.2.3.2. Excitation temperature using Saha-Boltzmann distribution 56

4.2.4. Electron Density 58

4.3. Powder samples and Calibration curves 61

4.3.1. Cu pellet 61

4.3.2. Cd pellet 62

CHAPTER 5. CONCLUSIONS 68

5.1. Conclusions 68

REFERENCES 69

List of Tables

[Table 1-1] Effects of heavy metal toxity on humans 17

[Table 3-1] Specification of Aurora Spectrometer 36

[Table 3-2] Specifications of LIBS setup 38

[Table 3-3] Solid samples 39

[Table 4-1] Laser energy and peak power density 41

[Table 4-2] Different laser spot sizes in distances to be moved focusing lens 42

[Table 4-3(a)] Spectroscopic parameters of the observed neutral copper (Cu I) lines 49

[Table 4-3(b)] Spectroscopic parameters of the observed singly copper (Cu II) lines 50

[Table 4-4(a)] Spectroscopic parameters of the observed neutral zinc (Zn I) lines 53

[Table 4-4(b)] Spectroscopic parameters of the observed singly zinc (Zn II) lines 54

[Table 4-5] Comparison between present work and literature for the Plasma parameters 60

[Table 4-6(a)] Spectroscopic parameters of the observed neutral cadmium (Cd I) lines 65

[Table 4-6(b)] Spectroscopic parameters of the observed singly cadmium (Cd II) lines 65

List of Figures

[Figure 1-1] Schematic diagram of the experimental setup 13

[Figure 2-1] Diagram of the energy levels involved in the lasing action for the Nd:YAG laser 20

[Figure 2-2] All the main LIBS processes 22

[Figure 2-3] Energy levels and electron transitions 24

[Figure 3-1] The control menu of the ASI LIBS GDT chemometric software which controlled the timing of the laser and Aurora spectrometer 37

[Figure 3-2] Temporal history of LIBS plasma 38

[Figure 4-1] Laser power versus Q-switch delay time 40

[Figure 4-2] SEM image, Spot size on starch pellet 40

[Figure 4-3] Laser spot size and power density 41

[Figure 4-4] Distance between intensity of the LIBS signal Cu I (510.5, 515.3 and 521.8 nm) emission line and the focusing lens 42

[Figure 4-5] Distance between intensity of the LIBS signal Cu I (510.5, 515.3 and 521.8 nm) emission line and the Collecting optics (Fibre optics) 43

[Figure 4-6] Dependence of the intensity LIBS signal of the emission line with target rotation speed 44

[Figure 4-7] Repetition rate versus signal intensity for Cu I lines 45

[Figure 4-8(a)] Emission spectrum of neutral and ionized copper plasma 46

[Figure 4-8(b)] The emission spectrum of copper foil 47

[Figure 4-9(a)] Energy level diagram of neutral ionized copper (Cu I) showing the prominent transitions observed in the present experiment 48

[Figure 4-9(b)] Energy level diagram of neutral singly copper (Cu II) showing the prominent transitions observed in the present experiment 48

[Figure 4-10] The emission spectrum of zinc foil 51

[Figure 4-11(a)] Energy level diagram of neutral ionized zinc (Zn I) showing the prominent transitions observed in the present experiment 52

[Figure 4-11(b)] Energy level diagram of singly ionized zinc (Zn II) showing the prominent transitions observed in the present experiment 53

[Figure 4-12] Variation of plasma temperature with spectrometer delay time 56

[Figure 4-13] Boltzmann plot based on eight neutral copper spectral lines at the 532nm laser, spectrometer delay 1000ns, 1Hz, surface having energy 15,2mJ 57

[Figure 4-14] Variation of plasma temperature with spectrometer delay time 58

[Figure 4-15] Cu foil: Plasma temperature and electron densities at different spectrometer delay 59

[Figure 4-16] Spectrum of Pellet (starch and copper) 61

[Figure 4-17] Calibration curves for copper (Cu I 324.7, 327.39nm) 62

[Figure 4-18] The emission spectrum of cadmium pellet 63

[Figure 4-19(a)] Spectroscopic parameters of the observed neutral cadmium (Cd I) lines 64

[Figure 4-19(b)] Spectroscopic parameters of the observed singly cadmium (Cd II) 64

[Figure 4-20] The LIBS signal intensity of the Cd I emission line at 2500, 5000, 7500 and 10000 ppm concentrations in Starch 66

초록보기

레이저 유도 파괴 분광법 (LIBS)는 거의 모든 형태의 시료에서의 원소 구성을 결정하는 데 있어 사용될 수 있는 분석 기술이다. 본 연구에서는 이러한 레이저 유도 파괴 분광법을 위한 분광기기를 직접 설계/개발하고, 개발된 분광기기로 고체 시료 내에 존재하는 중금속의 양을 정량/정성을 분석하였다. 고체 시료 중 미량의 중금속 원소를 정량/정성 분석을 위해 0.97×1010 W cm-2 (레이저 스폿의 크기는 ~ 200 ㎛) 광량의 Q-스위치 Nd:YAG레이저 기반의 CCD Aurora 분광기를 탑재하고 있는 LIBS 분석 장비를 개발하였다. 개발된 LIBS 분광기의 최적 조건을 마련하기 위해 표준 Cu 원소 시료를 이용해 레이저 광원의 세기에 따른 플라즈마 온도와 전자 밀도 수를 검정하였고, 이에 따라 100 ~ 200 ns의 휴지시간에 따른 Cu 방출 스펙트럼으로부터 9707 ~ 14088 K 의 여기 온도 구간에서 약 1015 cm-3 의 전자밀도 수를 형성함을 추정할 수 있었다.

오로라 LIBS 시스템은 중금속의 결정 (구리, 카드뮴)에 대한 보정 된 오염 물질은 펠렛 형태의 샘플 제시한다.

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