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ANACHEM FINALS > SPECTROPHOTOMETRY > Flashcards

SPECTROPHOTOMETRY Flashcards

1
Q

Study that observe how radiated matter and energy interact with each
other

A

Spectroscopy

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2
Q

It involves measurement of the light transmitted by a solution to determine
the concentration of the light – absorbing substance in the solutio

A

Spectrophotometry

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3
Q

Classification of Spectroscopic Methods

A
  1. Gamma Rays
  2. X- rays
  3. Ultraviolet (UV
  4. Visible
  5. Infrared
  6. Microwave
  7. Radio – frequency (RF)
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4
Q

provide the most widely used tools for
the elucidation of molecular structure as well as the quantitative
and qualitative determination of both inorganic and organic
compounds

A

Spectrochemical Methods

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5
Q

is a form of energy that is transmitted through space at enormous
velocities
- described as a wave with properties of wavelength, frequency, velocity,
and amplitude
- treated as discrete packets of energy or particles called photons or
quanta

A

Electromagnetic Radiation

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6
Q

It is a vector quantity of an electromagnetic wave that provides a measure of the electric of magnetic field strength at a maximum in the wave

A

Amplitude

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7
Q

-It is the time in seconds of electromagnetic wave for successive maxima or minima to pass a point in space

A

Period (p)

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8
Q

It is the number of oscillation that occur in one second
- oscillations of the electric field vector per unit time and is equal to 1/p

A

Frequency (v)

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9
Q
  • Is the linear distance between successive maxima or minima of a wave
A

Wavelength (λ)

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10
Q

Is the energy of a beam the reaches a given area per unit time
- Unit is in Watts (W

A

Radiant Power (P)

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11
Q

Is the radiant power-per-unit solid angle

A

Intensity

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12
Q

States that the relationship between wavelength and energy are
INVERSELY PROPORTIONAL.

A

Planck’s Law:

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13
Q

E = hv

A

Planck’s Law:

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14
Q

<400 nm wavelength

A

UV region

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15
Q

400 - 700 nm

A

visible spectrum

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16
Q

> 700 nm

A

infrared region

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17
Q

Samples are stimulated by applying energy

A
  1. Heat
  2. Electrical energy
  3. Light
  4. Particles
  5. Chemical reaction
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18
Q

Lowest Energy

A

Ground State

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19
Q

Higher energy

A

Excited State

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20
Q

Refers to the methods in which the stimulus is heat or electrical energy

A

Emission Spectroscopy

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21
Q
  • Refers to excitation of the analyte by a chemical reaction
A

Chemiluminescence Spectroscopy

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22
Q

s found in the light emitted by a firefly

A

Chemiluminescence

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23
Q

Chemiluminescence involving a biological or enzyme reaction is often
termed

A

bioluminescence

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24
Q

Amount of light absorbed is measured as a function of wavelength
- Absorption measurement can give both qualitative and quantitative
information about the sample

A

Absorption Spectroscopy

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25
Q

The emission of photons is measured following absorption

A

Photoluminescence Spectroscopy

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26
Q

Forms of Photoluminescence

A
  1. Fluorescence
  2. Phosphorescence
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27
Q

States that the concentration of the unknown substance is directly
proportional to the absorbed light (absorbance or optical density) and
inversely proportional to the amount of transmitted light (%
Transmittance).
- Mathematically establishes the relationship between concentration and
absorbance

A

Beer’s Law

28
Q

It is the amount of light absorbed
- It is proportional to the inverse log of transmittance
- Mathematically derived from %T (% transmittance)

A

Absorbance (A)

29
Q

It is the ratio of radiant energy transmitted (T) divided by the radiant
energy incident (I) on the sample.

A

Percent Transmittance

30
Q

Is an apparatus for measuring the
intensity of light in a part of the
spectrum, especially as transmitted
or emitted by a particular substances

A

Spectrophotometer

31
Q

The distance between 2 successive peaks; It is expressed in
terms of nanometer (nm)

A

WAVELENGHT

32
Q

: measurement of light intensity without
consideration of wavelength

A

PHOTOMETRIC MEASUREMENT

33
Q

measures light intensity in a
narrower wavelength. (spectrum of light)

A

SPECTROPHOTOMETRIC MEASUREMENT

34
Q

Parts of Spectrophotometer

A
  1. Light Source
  2. Entrance Slit
  3. Monochromator
  4. Cuvette/ Sample Cell/ Analytical Cell
  5. Exit Slit
  6. Photodetector
  7. Readout device
35
Q

Provides energy that the sample will
modify or attenuate by absorption
- The light is polychromatic ( all visible
wavelength is present)

A

Light Source

36
Q

emits radiation that changes in intensity
- most common

A
  • Continuum Source
37
Q

most commonly used light source in the
visible and near infrared region

A

Tungsten Light Bulb

38
Q

emits limited radiation and wavelength
- limited number of discrete line or bands of radiation

A
  • Line Source
39
Q
  • Mercury Arc
  • Deuterium Lamp
  • Hydrogen Lamp
A

UV Spectrum <400 nm

40
Q

Minimizes stray light
- Prevent entrance of scattered light
- “GATE” only permits the needed light

A

Entrance Slit

41
Q

Wavelength outside the band
- Can cause absorbance error
- Stray light limits the maximum
absorbance that spectrophotometer can
achieve
- Most common cause of loss of linearity
at high analyte concentration

A

STRAY LIGHT

42
Q

Isolates specific/individual
wavelength of the light
- DEGREE OF ISOLATION is
affected the the monochomator
and the with of entance and exit
sli

A

Monochromator

43
Q

Simple least expensive , not precise but useful
- Made by placing semi – transparent silver films on both sides of dielectric
such as magnesium fluoride produce monochromatic light based on the
principle of constructive interference of light waves.
- Usually pass a wide band of radiant energy and have an ion transmittance
of the selected wavelength

A

Colored Filters

44
Q

Wedge – shaped pieces of glass, quarts, or sodium chloride
- A narrow light focused on a prism is refracted as it enters more dense
glass
- Can be rotated allowing only the desired wavelength to pass through exit
slit

A

Prisms

45
Q

“Most Commonly Used”, better resolution than prism
- Made by cutting grooves ( parallel groves) or slit into an aluminized
surface of a flat pieceof crown glass - wavelengths are bent as they pass a
sharp corner

A

Diffraction Gratings

46
Q

the breaking up of a ray of light into component
wavelengths based on the principle that WAVELENGTHS BENDS AS THEY
PASS A SHARP CORNER

A

DIFFFRACTION

47
Q

It holds the solution whose concentration is to be measured
- It should be scratched free which can cause erroneous result
- Most common is rectangular shape, it is easier to maintain the length of
light

A

Cuvette/ Sample Cell/Analytical Cell

48
Q

It controls the with of light beam (band pass). It only allows a fraction of
the spectrum to reach the sample cuvette.
- Spectral purity of the spectrophotometer is reflected by the band pass –
the narrower the band pass, the greater the resolution.
- Accurate absorbance measurement requires a band pass < 1/5 the natural
band pass of the spectrophotometer.
- The degree of wavelength isolation is a function of the type of device used
and the with of entrance and exit slit

A

Exit

49
Q

– the range of wavelength between point at which
transmittance is one half peak transmittance

A

BAND PASS

50
Q

Converts transmitted radiant energy into an equivalent amount of electrical
energy

A

Photodetector

51
Q

– simplest and least expensive, low sensitivity and fatigue are the
downfall of this, needs frequent replacemen

A

PHOTOCELL

52
Q

contains anode and cathode in a tube, it gives off electron when
energy strikes it

A

PHOTOTUBE

53
Q

more sensitive than vacuum phototube
but less sensitive than Photomultiplie

A

PHOTOTRANSISTOR/PHOTODIODE

54
Q

most common, detect wide range (Visible and UV)
- 200 x more sensitive, it amplifies radiant energy
- detect very low light energy and quick bust of light

A

PHOTOMULTIPLIER TUBE

55
Q

It displays the output of the detection system

A

Read Out Device

56
Q

it is an important instrument that splits the monochromatic light into two
components
- One beam passes through the sample and the other through a reference
solution of blank
- The additional beam corrects for variation in light source intensity
- The absorbance of the sample can be recorded directly as the electrical
output of the sample beam

A

Double – Beam Spectrophotometer

57
Q

uses 2 photodetectors (for the sample beam and reference beam)

A
  • Double – Beam in Space
58
Q

uses one photodetector and alternatively passes the
monochromatic light through the sample cuvette and then reference cuvette
using a chopper

A
  • Double – Beam in Time
59
Q

Measures the light (wavelength) emitted by a single atom burned in
flame

A

Flame Emission Photometry FEP

60
Q

Measures the light absorbed by atoms dissociated by heat

A

Atomic Absorption Spectrophotometry

61
Q

Used to check wavelength accuracy

A

Didymium or Holmium Oxide Filter

62
Q

Verify absorbance
accuracy on linearity

A

Neutral Density filters and Dichromate Solution

63
Q

contain all the components of the solution to be
analyzed except to the one compound being tested

A

Blank Solution

64
Q

corrects absorbance caused by the color of the reagents

A

Reagent blank

65
Q

measures absorbance of the sample and reagent in the
absence of the end product and corrects the measurement for the optical
interference

A

Sample blank

ANACHEM FINALS (3 decks)

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