LAB spectrophotometry Flashcards

1
Q

factors affecting light source

A
range
spectral distribution within the range
source of radiant production
stability of radiant energy
temperature
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2
Q

two light sources

A

incandescent lamps

LASER

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3
Q

most common light source for visible region and near infrared

A

tungsten lamp

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4
Q

two forms of tungsten lamps

A

tungsten iodide

incandescent tungsten

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5
Q

inserted between lamp and sample for absorption of infrared radiation

A

heat absorbing filter

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6
Q

increases lifetime of tungsten lamp

A

iodine or bromine vapor

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7
Q

4 lamps used for measurement in the UV region

A

deuterium discharge lamp
hydrogen lamp
mercury-arc lamp
xenon lamp

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8
Q

deuterium discharge lamps emit continuous spectra down to _____

A

165 nm

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9
Q

has less stable and shorter life that deuterium discharge

A

hydrogen lamp

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10
Q

three types of mercury arc lamp

A

low pressure mercury arc lamp
medium pressure mercury arc lamp
high pressure mercury arc lamp

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11
Q

emits a sharp line for UV and visible regions

A

low pressure mercury arc lamp

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12
Q

used for calibration purposes only

A

low pressure emrcury arc lamp

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13
Q

has a continuum from UV to mid visible region

A

medium and high pressure mercury arc lamp

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14
Q

meaning of LASER

A

light amplification by stimulated emission of radiation

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15
Q

laser characteristics

A

extremely intense
focused
non divergent light

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16
Q

wavelength of laser:

argon fluoride

A

193 nm/ 248 nm

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17
Q

wavelength of laser:

helium cadmium

A

325 nm / 442 nm

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18
Q

wavelength of laser:

nitrogen

A

337 nm

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19
Q

wavelength of laser:

argon blue

A

488 nm

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20
Q

wavelength of laser:

argon (green)

A

514 nm

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21
Q

wavelength of laser:

helium- neon (green)

A

543 nm

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22
Q
wavelength of laser:
helium neon (red)
A

633 nm

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23
Q

minimizes and prevents entry of stray light into monochromator

A

entrance slit

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24
Q

isolates a specific wavelength of light

A

monochromator

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25
Q

monochromators are characterized with a specific : ?

A

bandpass

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26
Q

range of wavelengths permitted to impinge on the sample

A

bandpass

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27
Q

what is bandpass

A

width at more than half the maximum transmittance

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28
Q

three kinds of monochromators

A

filters
prisms
gratings

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29
Q

4 kinds of filters

A

colored glass filter
sharp cut off filter
narrow bandpass filter
interference filters

30
Q

colored glass filters are also known as

A

wide bandpass filter

31
Q

bandwidth of colored glass filters

A

50 nm

32
Q

not precise and has low transmittance of selected wavelength

A

colored glass filters

33
Q

eliminates lighg below a given wavelength

A

sharp cut off filter

34
Q

sharp rise in transmittance over a narrow portion of spectrum

A

sharp cut off filter

35
Q

2 or more sharp cut off filters and regular filters

A

narrow bandpass filters

36
Q

utilizes constructive interference

A

interference filters

37
Q

Cancelling out of undesired wavelengths

A

interference filters

38
Q

interference filters transmit: ?

A

harmonics

39
Q

interference filters require utilization of ?

A

accessory cut-off filters

40
Q

Separates white light into continuous spectrum by refractio

A

prism

41
Q

wavelength that is refracted by prism

A

shorter wavelength

42
Q

wavelength that passes through prism

A

longer wavelength

43
Q

most commonly utilized monochromator

A

diffraction gratings

44
Q

have parallel grooves etched onto a polished surface

A

diffraction grating

45
Q

Allows passage of the isolated wavelength to the sample

A

exit slit

46
Q

cuvets applied in visible range only

A

glass cuvets

47
Q

cuvets applied in UV range only

A

quartz cuvets

48
Q

cuvet that is difficult to manufacture and etched to indicate position for use

A

round cuvet

49
Q

cuvet with plane-parallel optical surfaces and constant light path

A

square cuvets

50
Q

what makes square cuvette better than round

A

Less error from

  1. lens effect
  2. orientation in spectrophotometer
  3. refraction
51
Q

Convert transmitted radiant energy to electrical energy

A

photodetector

52
Q

4 types of photodetectors

A

photocell
phototube
photomultiplier tube
photodiode

53
Q

another name for photocell

A

barrier layer cell

54
Q

made up kf film of light sensitve material like slenium on a plate of iron with silver covering

A

photocell

55
Q

disadvantages of photocell

A

curreny not easily amplified
temperature sensitive
not linera in hihh and low illumination

56
Q

similar witho photocell im which it utilizes outside voltage

A

phototube

57
Q

pjotosensitive cathode of phototube

A

rubidium, lithium

58
Q

detects and amplifies radiant energy which makes it 200x more sensitive than phototube

A

photomultipler tube

59
Q

gives off secondary electrons when hit bh a single electrode

A

dynodes or series of anodes

60
Q

Reverse-biased positive-negative-junction diode

A

photodiode

61
Q

1 array of photodiode

A

256- 2,0148 photodiodes

62
Q

resolution of photodiode which is not as sensitive as PMT

A

1-2 nm

63
Q

three variables in quality assurance

A

wavelength accuracy
stray light
linearity

64
Q

variable where actual wavelength indicated is the wavelength passed by the monochromator

A

wavelength accuracy

65
Q

how is stray light checked

A

Cut-off filters
NiSO4
NaNO2
Acetone

66
Q

variable where calibration curve should be a straight line

A

linearity

67
Q

range of visible spectrophotometer

A

400- 700 nm

68
Q

cuvettes used in visible spectrophotometer

A

plastic and glass cuvettes

69
Q

range of UV spectrophotometers

A

180-400 nm

70
Q

cuvettes used in UV spectrophotometers

A

quartz

71
Q

raange of infrared spectrophotometers

A

700-15000 nm