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cc lab > Electromagnetic Radiation > Flashcards

Electromagnetic Radiation Flashcards

1
Q

The principles that govern the analytic techniques and instrumentations in the lab fall into four basic areas:

A

Spectrophotometry
Luminescence
Chromatography
Electroanalytic Methods

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2
Q

a particle of electromagnetic radiation is known as

A

photon

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3
Q

is described as photons of energy traveling in waves

A

Electromagnetic radiation

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4
Q

Electromagnetic radiation is spread in the form of

A

electromagnetic waves

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5
Q

Electromagnetic radiation energy comes from the

A

SUN

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6
Q

The sun gets its energy from the process called______.

A

Nuclear Fusion

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7
Q

Distance between identical points on consecutive waves

A

Wavelength

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8
Q

Distance between origin and crest (or trough)

A

Amplitude

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9
Q

Number of waves that pass a point per unit time

A

Frequency

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10
Q

Speed

Formula

A

= wavelength x frequency

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11
Q

Wavelength is______ proportional to the frequency of the light wave

A

inversely

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12
Q

Energy is_____ proportional to the wavelength of light

A

inversely

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13
Q

T or F

The closer the two peaks are, the shorter the wavelength.

The shorter the wavelength, the larger number of photons will be contained in a given distance.

A

TRUE

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14
Q

More photons represents more energy, hence,_____ wavelengths represent____ energy

A

shorter

higher

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15
Q

: is a wave of alternating electric and magnetic fields

A

Light

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16
Q

Light: is a wave of alternating ______ and ______

A

electric and magnetic fields

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17
Q

2 types of light

A

Visible

Invisible

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18
Q

Invisible light

A

UV
Ifrared

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19
Q
  • wavelength falls below the visible region (190-340 nm)
A

Ultraviolet

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20
Q

Ultraviolet nm

A

(190-340 nm)

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21
Q

Infrared, Microwaves, Radio Waves nm

A

More than 700

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22
Q

Visible light Wavelength falls within

A

340-700 nm

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23
Q

■ also called as “transmitted light”

■ the one that our eyes can see

A

Reflected light

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24
Q

White light

■ also called as “________light”

A

polychromatic

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25
Q

■ composed of all the visible colors

■ made up of all colors of the rainbow because it contains all wavelengths

■ Ex: Ray of the sun

A

White light

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26
Q

■ Produces only one color

■ Ex: Laser

A

Monochromatic

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27
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 350-400

A

Violet

Yellow

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28
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 400-450

A

Indigo

Yellow

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29
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 450-500

A

Blue

Orange

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30
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 500-550

A

Green

Red

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31
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 550-600

A

Yellow

Indigo

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32
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 600-650

A

Orange

Blue

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33
Q

What is the color absorbed and the color emitted

Wavelength (nm) - 650-700

A

Red

Green

34
Q

In spectrophotometry, what we’re after is not the light that is_____ by the solution, but the light that is_____ by the solution

A

reflected

absorbed

35
Q

If the solution is red, the wavelength that is being absorbed is ______

A

green

36
Q

A hemolyzed (red) solution containing hemoglobin will absorb

A

green light at 540 nm

37
Q

● States that “ The concentration of a substance directly proportional to the amount of light absorbed and inversely proportional to the logarithm of the light transmitted”.

A

BEER-LAMBERT’S LAW

38
Q

The relative amount of light passing through the sample is known as_______

A

Transmittance (T)

39
Q

Percent Transmittance (%T)

A

T
—- x 100
I

40
Q

○ also called as “Optical Density”

A

Absorbance (A)

41
Q

is the measurement of the light transmitted by a solution to determine the concentration of the light-absorbing substance in the solution

A

Spectrophotometry

42
Q

Internal components of Spectrophotometer

A
  1. Light source
  2. Entrance slit
  3. Monochromator
  4. Exit slit
  5. Cuvette
  6. Photodetector
43
Q

○ “Exciter lamp”
○ Provide the electromagnetic radiation as visible infrared or ultraviolet light
○ Provides energy that the sample will modify by absorption

A

Light source

44
Q

Types of light sources

A

■ Tungsten/Tungsten-iodide lamp or Halogen Quartz lamp

■ Mercury Vapor Lamp

■ Deuterium Discharge Lamp

■ Infrared Energy Source

45
Q

most common light source at visible, near UV and near IR

A

Incandescent tungsten/
Tungsten-iodide lamp or Halogen
Quartz lamp

46
Q

Fluorometry

A

Mercury/ hydrogen lamp/
Xenon arc

47
Q

AAS (Atomic absorption spectrophotometry)

A

Hollow cathode lamp

48
Q

UV range; continuous light emission down to 165nm

A

Deuterium

49
Q

Infrared light

A

Merst Glower
Globar

50
Q

uses an electrically heated rod of rare earth element oxides

A

Merst glower

51
Q

uses silicon carbide heated to 1200 degrees Celsius

A

Globar

52
Q

○ Reduce stray light
○ Prevents scattered light from entering the monochromator

A

Entrance Slit

53
Q

the____ light is allowed to pass through the analytical cell, it would cause a deviation from the readings

A

stray

54
Q

○ Device that produces light of specific wavelengths from a light source

A

Monochromator

55
Q

▪ light radiation of a single wavelength

A

Monochromatic light

56
Q

• defines the range of wavelengths transmitted

• Determines the efficiency of monochromator

A

BANDPASS

57
Q

Generally, the narrow range of wavelength is the most desirable

Prisms & gratings = <5 nm
Interference filters = 10-20 nm

A

Bandpass

58
Q

Types of monochromator

A
  1. Prism
  2. Diffraction Gratings
  3. Interference Filters
59
Q

Wedge-shaped piece of (3) or some other material that allows transmission of light

A

Prism

glass, quartz, or sodium chloride

60
Q

Prism is based on_____ of light

A

refraction

61
Q

§ aluminized surfaces that has been cut into tiny grooves that can act as a prism and a slit

A

Diffraction Grating

62
Q

Diffraction Grating

Based on the principle that_____ bend as they pass a sharp corner.

The degree of bending depends on the______

A

wavelengths

63
Q

§ based on the principle of constructive interference of waves

§ Only light with desired wavelength which is reflected twice will be in phase and come out of the filter

A

Interference Filter

64
Q

It is constructed by using two parallel glass plates, which are silvered internally and separated by thin film of dielectric material (CaF2 , SiO, MgF2 ) of different refractive index

A

Interference Filter

65
Q

○ Exclusion of unwanted light from entering the monochromator

A

Entrance Slit

66
Q

○ allows only a narrow beam of the spectrum to pass through the cuvette
○ narrows down the light coming from the monochromator
○ Entering to the cuvette

A

Exit Slit

67
Q

● Analytical cell/sample holder

● Used to hold the solution in the instrument whose concentration is to be measured

● Made of material that does not absorb light in the wavelength range of interest

A

CUVETTE

68
Q

Types of cuvettes

A

Borosilicate
Quartz/ plastic
Alumina silica
Soft glass

69
Q

For alkaline solutions cuvette

A

Borosilicate glass

70
Q

For wavelength below 320 nm cuvette

A

Quarts or plastic

71
Q

Good at visible regions cuvette

A

Alumina Silica Glass

72
Q

Preferable for acidic solutions cuvette

A

Soft Glass

73
Q

● Converts transmitted light energy into an equivalent amount of electrical energy

A

PHOTODETECTORS

74
Q

Types of Photodetectors

A
  1. Barrier-Layer cell
  2. Photoemissive/phototube
  3. Photomultiplier
75
Q

○ Photocell or Photovoltaic
○ composed of light-sensitive materials (e.g. selenium on iron plate with transparent layer of silver)

A

Barrier-Layer cell

76
Q

○ when exposed to light, electrons in the light-sensitive material are excited and are released into the highly conductive silver
○ LEAST EXPENSIVE
○ NO NEED FOR POWER SOURCE

A

Barrier-Layer cell

77
Q

○ Similar to barrier-layer cell that it has photosensitive material that gives of electrons when light energy strikes it
○ Composed of positively charged anode and negatively charged cathode enclosed in a glass

A

Photoemissive/ Phototube

78
Q

○ Light strikes cathode → cathode emits electrons → electrons accelerate towards anode

○ Flow of electrons = current = no. of photons

○ Requires an external source of energy

A

Photoemissive/ Phototube

79
Q

○ Once light strikes the coated electron, electrons are emitted.
○ The electrons are attached to a series of anodes known as_____

A

Photomultiplier (PM) tube

dynodes

80
Q

The_____ tube can amplify the amount of light energy therefore it can measure even the very low light waves

A

Photomultiplier

81
Q

○ displays the amount of light transmitted

A

Read-Out device

82
Q

Read-out devices

A
  1. Meter
  2. Digital
  3. Recorder

cc lab (46 decks)

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