Instrument1

1
??????????? ?????????????? ?????????????????????
Instruments for Optical Spectroscopy
??.?????? ????????????
2
Instruments for Optical Spectroscopy
?????????????????????????????????????????????
emission, absorption ??? fluorescence
spectroscopy ????????? ???????????????????????????
???? UV, visible ???? IR radiation
?????????????? optical instrument
????????????????????????????????????????????
3
Instruments for Optical Spectroscopy
???????????????????????????? (spectroscopic
instruments) ?????????????????? 5 ???? ??? 1.
???????????????? (radiation source) 2.
???????????????????? (wavelength selector) 3.
?????????????????? (sample container) 4.
???????????????/???????????? (radiation
detector/transducer) 5. ??????????????? (signal
processor) ???????????????? (readout)
4
?????? 1 ????????????????????????????? optical
spectroscopy
5
Instruments for Optical Spectroscopy
???????? absorption ???????? source ??????
wavelength selector ??????????????????????????????
????????????? ???????????????? ??????????????
sample container ????????????????????? detector
??????????????????????? ?????????????????????????
??????? signal processor ??? readout
?????????????????????? ?????????? wavelength
selector ??? sample container ??????????
6
Instruments for Optical Spectroscopy
???????? fluorescence ???????? source ????
wavelength selector (1) ?????????? excitation
wavelength ?????????????????????? analyte
???????????????????? fluorescence ???????????
wavelength selector (2) ?????????? emission
wavelength ??????????? fluorescence
?????????????????????????? source
7
Instruments for Optical Spectroscopy
??????????????????? emission ??????????
radiation source ???????????????????????? plasma,
flame ???? heated surface ?????????????? ?????
analyte ???????????????????? ????????????????????
???????????? ?????????????????????
8
Optical Materials
????????????????????? windows, lenses,
mirrors, prisms, sample containers ???
spectroscopic instruments ???????????
(transparent) ???????????????????? ??????
visible ??????? silicate glass ?????? UV
(lt380 nm) ??????? fused silica ???? quartz
?????? IR ??? halide salt (KBr, NaCl, AgCl)
9
???????????????? (Spectroscopic Sources)
Absorption ??? fluorescence spectrometer ??????
external radiation source radiation source
???????? ? ??????????? (stability) ???
??????? ??? output power ?????
radiant power ??? source ??????????? exponential
??? ?????? (?????????????)
????????????????? ????????????????
??????????????? (voltage regulator) ?
????????????????????? (intensity) ???
???????????????????? ? ????????????? spectral
range ?????
10
???????? 1 Continuum Sources for Optical
Spectroscopy
11
???????? 2 Line Sources for Spectroscopy
12
???????????????? (Spectroscopic Sources)
?? optical spectroscopy ??????? continuum
sources ??? line sources Continuum UV/Visible
Sources ? ?????? UV ??????? deuterium lamp
??? hydrogen lamp ? ?????? visible ???????
tungsten lamp
13
???????????????? (Spectroscopic Sources)
?????? 2 (?) deuterium lamp (?)
emission spectrum ??? deuterium lamp
14
???????????????? (Spectroscopic Sources)
(?)
(?) ?????? 3 (?)
tungsten lamp. (?)
emission spectrum ??? tungsten lamp
15
Wavelength Selectors

• ???????????? polychromatic radiation
  (?????????????????????) ??????? monochromatic
  radiation (??????????????????????)
• ???????????? ??????????????????? monochromatic
  radiation ????????????????????????????? ????????
  band (???)

Wavelength Selector
16
Wavelength Selector
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(No Transcript)
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Wavelength Selectors

• ?????????????????????????
• ????? selectivity ??? sensitivity ?????????????
• ????????????????? Beers law ?????????
  polychromatic radiation ???????????? absorption

19
Sensitivity
?????? (Sensitivity) ?????????????????????
??????????????????????????????????????????????????
?????????????????????????? analyte ?????????????
???????????????? sensitivity ??? 1.
??????? (slope) ??? calibration curve
??? calibration curve ???????????? sensitivity
????? 2. ???????????? (reproducibility)
?????????????? (precision)
???????????????? ??? reproducibility
???? precision ??? sensitivity ?????
20
Detection Limit
?????????????????? (Detection limit or Limit
of detection, LOD) ???????????????????????????????
??? analyte ??????????????????????????????????????
?????????? Detection limit ???????????????????
analytical signal ??????????????????????? blank
signal
21
Signal, Noise
?????? (Signal) ??? ???????????? output
????????????? ??????????? (Noise)
?????????????????????????????????????
???????????????????? output ??????????????????????
??????????????????????????????? (standard
deviation) ????????? ????????????????????????????
???? (Signal-to-noise ratio, S/N)
???????????????????????? output / standard
deviation ???????????????????????????????????????
?????????????
22
???????? 3 Wavelength Selectors for
Spectroscopy
23
Radiation Filters

• ?????????????????????????? continuum source
  ??????? ?????? band of radiation ????????????????
  visible
• Filters ?????????????????????? 2 ???????
• 1. Interference filters
• 2. Absorption filters

???????? absorption ?????? interfernce filters
??????????????????????????????????????????????????
????????? absorption filters
24
Absorption Filters

• ?????????????? ?????????????????? (absorption)
  ?????
• ?????????????? band ?????? visible
• effective bandwidths 30250 nm
• ??? effective bandwidth ???????
  transmittance ???????????????

25
Absorption Filter
?????? 5 absorption filter ??????????????????????
??? ????????????????? (?????????????) ???????
26
Cutoff Filter
Cut-off filter ???? absorption filter
???????????????????????????????????????????????
(Long pass filter) ??????????????????? (Short
pass filter)
27
Absorption Filter
28
Absorption Filter

• Filter ?????????? ??????? ????????
• Filter ?????????????? band ??????????????????????
  ????????????????????????????????????????????
  filter ??????????????????????? filter
  ??????????????????????????????????????????????????
  ??????????????????

29
Interference Filters

• ????????? UV, visible ??? IR (?????????????????
  14 ?m)
• ????????????????????????????? (optical
  interference)
• effective bandwidths ??????????? ????????????
  520 nm

30
Interference Filters
?????? 7 Schematic cross section of an
interference filter.
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Interference Filters
Interfernece filter ?????????????????????????
?? (dielectric) ????????? (??????????? CaF2,
MgF2) ???????????????????????????????????????????
??????????????????????????????????????????????????
???????????????? ????????????????????????????????
?????????????? 2 ?????????????????????????????????
?????????? dielectric layer
????????????????????????????? transmitted
radiation ????????????????????????????
32
Interference Filters
Dielectric ??? ???????????????????
(nonconductors) ??????????????????????????????????
???? ????????? dielectric ????????? (optically
transparent) ?????????????????????????????????????
??????? (absorb) ?????????? (reflect) ????????
33
Interference Filter
?????? 8 Schematic to show the conditions for
constructive interference.
34
Interference Filter
????????????????????? interference filter
???????? ? ???????????????????? 1
?????????????????? ????????????????????????
???????????????????????????????????? 2
???????????????? ?????????????????? 2 ?????? 1?
????????? 2 ???????????????? ??????????????????
?????????????????? 2 ?????????????????????????????
????????????????????? 1 ??????????????????????????
?????????????????????????????? ???????????????????
????? (constructive interference) ??????? filter
????? ??????????????????????????????????????
??????????????????? (destructive interference)
35
Interference Filter
??????????????????????????? interference filter
(?max) ?????????????????????????????????????
36
Interference Filter
?????? 9 Interfernce filter ?????????????????????
???????????
37
Radiation Filters
Interference filter ??? transmitted radiation
????? bandwidth ???????????? transmission
??????? absorption filter ????????????????
38
Monochromators

• ????????????? monochromators
• ??????????? (entrance slit)
• ?????/?????????????? (collimating mirrors/lens)
• ???????????????? (dispersing medium)
• ?????? ?????? (prism) ??????? (grating)
• ?????/?????????? (focusing mirrors/lens)
• ?????????? (exit slit) ??? ?????????? (focal
  plane)
• ????????? ????? entrance ??? exit windows

39
Monochromators
????????? 11 ??????????????????????????????????
?? 2 ??????????????? ?1 ??? ?2 (?1 gt ?2) ???????
monochromator ???????????? (entrance slit)
???????????????????????????????/?????????
(concave mirror/lens) ???????????????????????????
???????????????????????????????????????????
(angular dispersion) ??????? 2 ?????
????????????????????????????????????/?????????????
????????????????????? (focal plane) AB
??????????????????????????????????????????????????
????????????? (?2) ???????????? exit slit ???????
detector
40
?????? 11 (a) Czerny-Turner grating
monochromator. (?1 gt ?2)
41
Monochromators
?????? 11 (b) Bunsen prism monochromator. (?1 gt
?2)
42
Monochromators
? effective bandwidth ??? monochromator ???????
? ???????????????????????????????? ?
??????????????????????? (slit width) ?
???????????? (focal length) ? effective bandwidth
??? monochromator ????????????????????????????????
????????????? 1 20 nm ? monochromators
????????????????? slit width ??? ?????? slit
??????? effective bandwidth ?????????????????????
??????????????????????????????? ????????????
effective bandwidth ????????????????????
sensitivity ??? detector
43
Monochromators
? ?????????????????? (qualitative analysis)
??????? slit ?????? bandwidth ????????????????????
????????????????????? peak ???? ?
?????????????????? (quantitative analysis)
??????? slit ???????????????????????????????
(detector system) ?????????????????????????
????????? reproducibility of response ???????
44
Prism

• ???????????????????????? ???????? (refraction)
  ??????????????????? (refractive index)
  ???????????????????????????
• ??????????????????????????????????????
  ???????????????????? ????????????????????????
  ??????????????????
• ?????????????????????????????????????????????
  ???

45
Prism
?????? 12 ???????????????????????????????????????
?????????????
46
Prism
????????????????????????????????????????????????
47
Prism

• ?????????????????? visible ??????????
• ?????????????????? UV ?????? quartz / fused
  silica (????????? visible ???????)

48
Gratings

• ??????????????????????????????????????????????????
  ????????????????
• ??????????????????? UV / visible ????? 300 2000
  ????/mm ??????????????????????????????? 1200
  1400 ????/mm

49
Gratings

• Echellette Grating
• ???? reflection grating ??????????????????????
  ??? ?????????????????????????????????????????????
  ? (????????? ...) ???????????????????????
  (diffraction) ??????????????????? ????????????
  (reflection) ??????????????????????
• ?????????????? board face ???? point source
  of radiation ??? reflected beam 1, 2, 3 ????
  interfere ????????????? ????????????
  constructive interference path lengths
  ???????????????????? n ??????? wavelength of
  incident beam

50
Gratings
Grating Equation n? (CB BD) CB d sin i BD
d sin r n? d (sin i sin r)
?????? 14 (a) Diffraction of radiation from a
grating.
51
Gratings
????????????????? monochromatic radiation
??????????????????????????? i ????????????????????
? ?????????????????? (diffraction)
??????????????????????????????? diffracted
beam ????????????????? (interfernce)
????????????? ??????????????? (constructive
interfernce) ???????????????????? r
??????????????????????????? (?) ???????? n?
d(sin i sin r) n ??????????????????
(diffraction order) ?1, ?2, ?3, d
?????????????????????????????????? i
?????????? (incident angle) r ?????????
(reflected angle)
52
Gratings
???????? n? d(sin i sin r) ???????
??????????????????????????????????????? r
???????? ???? ????? first-order line (n 1)
???????????? 800 nm ?????? r ???? second-order
(400 nm) ??? third-order (267 nm) lines
?????????????
53
Gratings
?????? 14 (b) Diffraction of radiation from a
grating.
54
Gratings
????????? first-order line ??????????????????
???????????????????????????? first-order line 90
??? incident power higher-order lines
????????????????? filters ???? ???????????????????
??????????????????????? 350 nm ????????
higher-order radiation ???????????????????
first-order radiation ?????? visible ???
55
Gratings
???????? monochromator ?????? echellette
grating ????????????? prism monochromator
??????????????????????????????????????????????????
(linear dispersion) ?????????????? monochromator
?????????
56
Gratings
Concave Gratings concave grating
??????????????????????????? monochromator ??????
concave grating ????????? collimating ???
focusing mirrors ???? lenses ?????????????????????
?????????????????????????????????? exit slit ???
monochromator ?????? concave grating
???????????????????????? ????????? ??????????
optical surfaces ?????????????????????????????????
?? monochromator ???????
57
Gratings
Halographic Gratings holographic grating
????????????????????? laser technology
??????????????????? (optical technique)
?????????????????? (mechanical technique)
??????????????????????? ?????????????????????????
???????????????????? optical instruments
??????????? holographic gratings ??????????
??????????????????????????????????????????????????
????????????????? ??????????????????????
(scattering) ?????????????????????
58
Sample Container
59
Sample Container
?????????????????? ???????????? cell ????
cuvette ???????????????????????? (transparent)
?????????????????????????? path length
?????????? ? quartz / fused silica ?????????
UV (lt 350 nm) ??? ???????????? visible
????? 3,000 nm (3 ?m) ?????? IR ? silicate
glass ????????? 3502,000 nm ?????????????? ????
quartz ??????????????? plastic cell ??????
visible ? ???? sodium chloride ????????? IR
60
Sample Container
???????? 4 Cell material
61
(No Transcript)
62
Sample Container

• ? Cells ??????????? windows ?????????????????????
  ??????????????????????????????????????????????
• Cell path length ???????????????????????? UV ???
  visible ??? 1 cm ??????????????? 0.1 10 cm
• Cell ???????????? ????????? ??????????????????????
  ???????????????????????????????????????? ??????
  cell ???? cell holder ????????????????????????????
  ?????????????? (?????????????????? cell ???)
  ??????????????????????????? path length ???
  reflection losses ??????????

63
Sample Container

• ?????????? ?? ??????????????????
  ??????????????????????????????????????????????????
  ??????????? ?????????????????????????????????????
  ???????? ???????????? window ????????????????????
  ????????
• ?????????????????? (matched cell)
  ??????????????????????????????????????????????????
  ??? ????????????????????????????????? path length
  ???????????
• ?????????????????? (matched cell)
  ???????????????? (calibrate) ?????????????????????
  ??????????? absorbing solution

64
Detector and Transducer
??????????? spectroscopic information
????????????? radiant power ??? transmitted,
fluoresced ???? emitted radiation
???????????????????????????????????????
?????????? (detector) ????????????????????????????
??????????????????? ???? photographic film
(????????????????????????????????????????????????)
?????????????????? (????????????????????????????
???) ??????????? detector ????????????????????
????? visible ???????????????????? (electrical
signal) ??????????????????????????????????????????
?????????????
65
Detector and Transducer
??????? (Transducer) ???? detector
????????????????????? ???? ?????????????? pH ???
??????????? ???????????????????? (electrical
signals) ??????????????????????????? manipulated
??????????????????????????????????????????????????
?????????? ?????????????????? ????????????
(radiation transducer)
66
Detector and Transducer
Ideal Radiation Transducer 1. ???????????????????
??? low level of radiant energy
??????????????????????? 2. ??????????????
(electrical signal) ??????????????????? noise
level ??? (S/N ???) 3. ??????????????????????????
???????????????? radiant power P ????????
67
Detector and Transducer
S KP Kd
S ??????????? (electrical signal) ???
detector ???????? ????? ?????????? ???? ????? P
radiant power K ????????????????
sensitivity ??? detector ?????????????????????????
?????? radiant power Kd dark current
(??????????????????? detector ????????????????????
??)
68
???????? 5 Detectors for Spectroscopy
69
Types of Radiation Transducers
1. Photon (Photoelectric) Detectors

• ?? reactive surface ???????????????? ?????????
• ?????????????????? (photoemission)
  ????????????????
• (photocurrent)
• ?????????????????????????????????????
  (conduction band)
• (photoconduction) ????????????????
  (conductivity)
• ?????????
• ????????????????????? UV, visible ??? near-IR

70
Types of Radiation Transducers
2. Heat Detectors
??????????????? IR ?????????????????????????????
blackened material ??????????????????????????
71
Photon Detectors
Phototubes
Phototube ?????????? cathode ????????????????
anode ????????????????????????????????????????????
?????????????? cathode ?? photoemissive
material ???? ??????????? ????????????????????????
? ????????????????????????????????????????????????
??????????
72
Phototubes
? ???????????????????????????????????
?????????????????? cathode ?????????????????
???????????? photoelectrons ?????
photoelectrons ???????????????????????????????????
???????? radiant power ????????????????????
cathode ? ??????????????????? ? 90 V ???
electrode photoelectrons ????????????????????????
???????????? anode ??????????????
????????????????????????? ????????????
photocurrent photocurrent ???????????????????
???????????? radiant power ???????? photocurrent
???????????????????????
73
Photomultiplier Tubes (PMT)
Dynodes (1-9)
Quartz envelope
Grill
Anode
Photoemissive cathode
?????? 17 Diagram of PMT.
(a) Cross section of the tube. (b) Electrical
circuit.
74
Photomultiplier Tubes (PMT)

• PMT ?????????? photocathode ??? anode
  ???????????? phototube ????? electrodes ??? 9
  ??????????????? dynodes ??? sensitive ????
  phototube
• ????????????????? photocathode ???????
  photoelectrons
• photoeletrons ??? cathode ????????? (accelerate)
  ????? dynode ????????????????????????????????????
  cathode 90 V
• ?????????? accelerated photoelectrons
  ???????????? dynode ?????????????????????????????
  ???????? secondary electrons

75
Photomultiplier Tubes (PMT)

• secondary electrons ??? dynode 1 ??????????????
  dynode 2 ?????????????????????????????? dynode 1
  ???? 90 V ????????? electrons ????????????
  (electron amplification)
• ????????????????????????????? ???????? dynode 9
  ????????????????????????????????????????? 105
  107 ???
• ?????????????????????????????????????????? anode
  ?????????????????????????????? dynode 9 ???? 90 V
  ????????? photocurrent ????????????????????????

76
Silicon Photodiodes

• Crystalline silicon (Si)
• ???? ???????????? (semiconductor) ???????
  ????????????????????????? ??????????????
• Si ??????????????? 4 ??????????????????? 4 ???
  ?????? Si ???????????????????????????????????????
  Si ????????? 4 ????? ?????????????????? 4 ?????
• ??????????????? ??????????????????????????????????
  ??????????????????????????????????????????????????
  ????????????????????????????

77
Silicon Photodiodes

• ??????????????????????????????????????????????
  ???????? hole ????????????????????????????????????
  ??????????????????????????????????????????
  ????????? positive hole ????????
  ???????????????????? ??? positive hole
  ??????????????????????????????????????????????????
  ????????? ???????? semiconductor ??????????
• ????????????? Si ?????????????? doping
  ????????????????????????????????? 5 ???? 3
  ????????????????????????????? (1 ppm)
  ??????????????????????????????????? Si

78
Silicon Photodiodes

• ??? dope ???? Si ???????????? 5 ???? arsenic (As)
  ????????????????? 4 ?????? As ?????????????? Si
  ????????? ???????????????????????????? 1
  ????????????????????? ????????????????????????
• semiconductor ?????????????????????????????????
  (negative charges) ???????? n-type semiconductor

79
Silicon Photodiodes
??? dope ???? Si ???????????? 3 ???? gallium (Ga)
??????????????????????? ????? 3 ??? ????????????
positive hole ??????????????????????????? semicond
uctor ????? hole ?????????????? (positive
charges) ???????? p-type semiconductor
80
Silicon Photodiodes
Silicon technology ?????????????????????????????
pn junction ???? pn diode ????????????????????????
????????????????????????
81
Silicon Photodiodes
?????? 19 (a) Flow of electricity under forward
bias. (b) Formation of depletion layer, which
prevents flow of electricity under reverse bias.
82
Silicon Photodiodes
???????? silicon diode ??? forward-bias
(????????????? dc source ??? p region
???????????? n region) ????????????
?????????????????????????? n region ??? positive
holes ?? p region ????????????????? pn junction
??????????????????????????????? ????????? dc
source ??????????????????????????? n region
??????????????????????????? ?????????????????????
???? p region ????????? holes ????????????????????
????????? pn junction ???
83
Silicon Photodiodes
???????? silicon diode ??? reverse bias
(???????????? dc source ??? p region
????????????? n region) ??????????????????????????
???????????? n region ??? positive holes ?? p
region ?????????????????? junction ?????????
depletion layer ?????????????? (?????????????????
10-6 ???? 10-8 ??????????????????????? forward
bias) silicon diode ????????????????
????????????? (current rectifier)
84
Silicon Photodiodes
85
Silicon Photodiodes

• Silicon diode ????????? reverse bias
  ????????????? photodetector ??? ?????????
  UV/visible photons ?????????? depletion layer ??
  pn junction ??????????????????????????????????????
  ????? valence band ????? conduction band
  ????????? electron-hole pairs ?????????
  ??????????????????????????????????????????????
  radiant power ????????
• Silicon photodiode sensitive ??????? phototube
  ???
• sensitive ????????
  PMT

86
Diode-Array Detectors

• ?????? 21
• A reversed-biased linear diode array detector
• cross section
• (b) top view.

87
Diode-Array Detectors

• ???? silicon photodiodes ?????????????????????
  silicon chip ??????????????????? (????? diode
  ????????????????? 0.025 mm)
• ?????? diode-array detector 1 ???? 2 ???
  ???????????????????????????????? monochromator
  ??????????????????????????????????????????????????
  ???????????????????????
• ?????????????????????? ??????????? reverse bias
  ?????????????????????? radiant power
  ??????????????????
• ????? multichannel instruments
• ????????????? PMT (???? sensitivity, dynamic
  range, S/N)

88
Diode-Array Detectors
?????? 22 Photodiode arrays of various
sizes. The arrays contain 256, 512, 1024, 2048,
and 4096 diodes.
89
Charge Transfer Device (CTD) Detector

• ?????????????????? PMT ??????????????
  multichannel instruments ??? ?????????????????????
  ??? CTD detector ???????
• ???? two dimentional detector ????????? detector
  elements ????????????????????????? ???? detector
  ?????????????????? detector element 244 ???
  ?????????????????? detector element 388 ???
  ?????????????? two dimentional array ??? 19,672
  individual detectors ???? pixels ?? silicon chip
  ????????????????? 6.5 mm x 8.8 mm
  ??????????????? two-dimentional spectrum ???

90
Charge Transfer Device (CTD) Detector
91
Charge Transfer Device (CTD) Detector

• pixel ???????? CTD detector ?????????? electrode
  2 ??? (??? pixel ?? electrode ??????? 2 ???)
  ????????? silica (SiO2) layer ????????????????
  electrode ??? n-doped silicon ??????????????
  metal oxide semiconductor capacitor
  ??????????????????????????????????? doped silicon
  
• ???????????????????????? electrode
  ?????????????????????????????? electrode ????????
  potential well positive holes
  ???????????????????????????? silicon
  ????????????????????????? potential well
  ???????????????????????????? ?????????????????????
  105106 ????????? overflow ???????? pixel
  ?????????

92
Charge Transfer Device (CTD) Detector
???????????????????????????????????? CTD detector
??????????? ????? 2 ???? ???
1. Charge-injection device (CID) detector
?????????????????????????????????????????????????
???????????????????????????? electrode
????????????? electrode ????? 2 Charge-coupled
device (CCD) detector ????????
?????????????????????????? charge sensing
amplifier ?????????????
93
Signal Processors and Readouts
Signal Processors

• ??????????????????????????
• ?????????????????? detector
• ???????????????? dc ? ac
• ?????????? (phase) ?????????
• ?????????????????????????????????????
• ??????????????????????????????? ???? ??????????
  (integrate) ?????????? (differentiate)
  ???????????????????? ???

94
Signal Processors and Readouts
Readout devices

• readout devices ??????????????????????????????????
  ????
• digital meters
• scale of potentiometers
• recorders
• cathode-ray tubes
• monitors of microcomputers

95
Ultraviolet-Visible Photometers and
Spectrophotometers
??????????????????????????????????????????????
??????????? (????????? 1) ???????????
?????????????????????? ?????? ? ???????????
(Photometers) ??? spectroscopic instrument
?????? filter ??????????????????????? ???????
transducer ???????????? radiant powers ???????
electrical signals photometer
????????????????????????????? ????? ??????????
96
Ultraviolet-Visible Photometers and
Spectrophotometers

• ? ?????????????? (Spectrometer)
• ??? spectroscopic instrument ??????
  monochromator ???? polychromator ???????
  transducer
• ? ?????????????????? (Spectrophotometer)
• ??? spectrometer ????????????????????????
  radiant power ???????? 2 ????? ????????
  absorbance (A log P0/P ? log Psolvent/Psolution)
  
• spectrophotometer ??????????
  ??????????????????????????????????????????
  ????????????????? absorption spectra ???

97
Ultraviolet-Visible Photometers and
Spectrophotometers
???? Photometers ??? spectrophotometers
??????????? ?????????????????????????
(single-beam instruments) ??? ????????????????????
?? (double-beam instrument)
98
Single-Beam Instruments
???????? filter ???? monochromator ????
reference cell ???? sample cell ???????????
photodetector
99
Single-Beam Instruments
?????? T ???? single-beam instrument ?? 3
??????? 1. 0 T calibration or adjustment ???
shutter ??????????????????? radiation source
??????? photodetector ????????????????????????
0 T 2. 100 T calibration or adjustment ???
cell ???????? blank (??????????? solvent) ????
cell holder ???? shutter ????????????????????????
?????????????????????????????????????????? 100
T 3. Determination of T of analyte ??? cell
???????? sample ???? cell holder ???? T ???? A
100
Single-Beam Instruments
?????? transmittance ????????????????
(reproducibility) ??? ??? radiant power ???
source ????????????????? 100 T ??????? T ???
analyte ???????????????????????????????????
voltage supply ???????? single-beam
instrument ????????????????????? ???????
????????????????? ???????????????????????????????
??????????????????????????
101
Single-Beam Spectrophotometers
?????? 25 Spectronic 20 spectrophotometer.
102
Single-Beam Instruments

• Spectronic 20
• ???? single-beam spectrophotometer
  ?????????????????????? ?????????????????????
  visible ???????????????? ?.?. 1950
  ????????????????????????????????????
• ??????????????? occluder ?????????????????????????
  ??????????? detector ?????????????????????????????
  ? cell holder (??????? detector ??????
  ???????????? 0 T calibration or adjustment)
• light-control device ?????????????? V
  ??????????????????????????????????????????????????
  ?????????????? exit slit

103
Single-Beam Instruments
Specification of Spectronic 20 spectral range
340 - 950 nm Spectral band-pass 20
nm wavelength accuracy ? 2.5 nm Photometric
accuracy ? 2 T
104
Double-Beam Instruments
105
Double-Beam Instruments
Double-beam-in-space instrument
??????????????? V ????????????? beam splitter
???????????? 2 ?? ?????????????? reference cell
????? photodetector ?????????????
??????????????????? sample cell ????? matched
photodetector outputs ????????????????
???????????????????????????????????? ?????????
106
Double-Beam Instruments
?????? 26 Instrument designs for photometers and
spectrophotometers (c) double-beam-in-time
instrument.
107
Double-Beam Instruments
Double-beam-in-time instrument ???? sector
mirror ?????????? ????????????????? 2 ?????????
(???? milliseconds) ??????????????????
??????????? reference cell ????? photodetector
?????????????????????????????? sample cell ?????
photodetector ??????????? ???????????????????????
??????? grid mirror ?????????????????? reference
cell ??????? ????????????????? sample cell
??????? double-beam-in-time instrument ???????
double-beam-in-space instrument ????????????????
matched detectors ????????
108
Double-Beam Instruments
???????? double-beam instruments

• ????????????????????? radiant output ??? source
  ????????????????? detector ??? amplifier
• ????????????????????? radiant output ??? source
  ????????????????????????????
• ???????????????????? absorption spectra
  ??????????????

109
Multichannel Instruments

• ??? scan spectrum ???????????????????
  ?????????????????????????????????????????
  ?????????????????????????????????
• multichannel instruments ??? scan spectrum
  ????????????????????? 1 ??????
• Photodiode arrays ??? charge transfer devices
  ??????????????????????????????????????????????
  ??? ????????multichannel instruments ??????
  UV/visible absorption
• Resolution ??? multichannel instruments ?????????
  (resolution of 1 nm is possible)

110
Multichannel Instruments
111
Multichannel Instruments
multichannel instrument ??????? single-beam
design ????????????????? (dispersion device)
???? ??????? ?????????? sample / reference cell
??? photodiode array ???? charge transfer devices
???????????????? Resolution ??? multichannel
instruments ???????????????????????
112
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