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FINALS! ANAMETH LEC > Spectroscopy > Flashcards

Spectroscopy Flashcards

1
Q

A sample in a 1.0-cm cell transmits 80% light at a certain wavelength. If the absorptivity of this substance at this wavelength is 2.0, what is its concentration?

A

c = 0.050 g/L

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2
Q

absorption FORMULA

A

A = -log T = log 1/T = log P0/P =abc

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3
Q
A
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4
Q

Transmittance Formula

A

T = P0/P

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5
Q

PERCENTAGE TRANSMITTANCE

A

%T = P0/P x 100

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6
Q

amount of monochromatic radiation absorbed by a sample

A

Bouguer–Lambert-Beer’s law/
Beer’s Law

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7
Q

study of the interaction of electromagnetic radiation in
all its forms with matter

A

spectroscopy

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8
Q

Latin “spectron”

A

ghost/ spirit

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9
Q

σκοπειν

A

to see

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10
Q

Method involves in the interaction of light

A

excitation and detection

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11
Q

TRUE OR FALSE

Electromagnetic radiation moves through a medium other than a vacuum with a velocity, v, less than that of the speed of light in a vacuum

A

TRUE

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12
Q

Change in intensity I of incident light

A

ABSORPTION

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13
Q

Excitation induces emission of light from the sample

A

EMISSION

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14
Q

emission from excited electronic singlet states

A

FLUORESCENCE

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15
Q

emission from excited electronic triplet states

A

PHOSPHORESCENCE

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16
Q

light scattering involving vibrational transition

A

RAMAN SCATTERING

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17
Q

Two types of spectrometers

A

DISPERSIVE
FOURIER TRANSFORM

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18
Q

TRUE OR FALSE

A source of electromagnetic radiation must provide an output that is both intense and stable in the desired region of the electromagnetic spectrum.

A

TRUE

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19
Q

A source that emits radiation over a wide range of wavelengths,
with a relatively smooth variation in intensity as a function of
wavelength

A

continuum

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20
Q

emit radiation at a few selected, narrow wavelength ranges

A

LINE SOURCES

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21
Q

TRUE OR FALSE

The ideal wavelength selector has a high throughput of radiation and a narrow effective bandwidth

A

TRUE

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22
Q

Why is high throughput desirable?

A

because more photons pass through the wavelength selector, giving a stronger signal with less background noise

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23
Q

provides a higher resolution, with spectral features separated by more than twice the effective bandwidth being resolved

A

narrow effective bandwidth

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24
Q

The simplest method for isolating a narrow band of radiation

A

absorption or inference filter

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25
Q

work by selectively absorbing radiation from a narrow region of the electromagnetic spectrum

A

ABSORPTION FILTER

piece of colored glass

26
Q

use constructive and destructive interference to isolate a narrow range of wavelengths

A

INTERFERENCE FILTERS

27
Q

more expensive, but have narrower effective bandwidths, typically 10–20 nm, with maximum throughputs of at least 40%.

A

INTERFERENCE FILTERS

28
Q

LIMITATIONS OF USING FILTERS

A
  • Do not allow for a continuous selection of wavelength
  • Available for only selected nominal ranges of wavelengths
29
Q

have a diffraction grating to disperse the radiation into its component wavelengths

A

MONOCHROMATORS

30
Q

simultaneously allows source radiation of all
wavelengths to reach the detector

A

INTERFEROMETERS

31
Q

The signal at the detector shows intensity as a function of the moving mirror’s position, expressed in units of distance or time

A

interferogram

32
Q

time domain spectrum is also called

A

interferogram

33
Q

convert a signal consisting of photons into an easily measured electrical signal

A

Modern detectors

34
Q
A
35
Q

used for optical
spectroscopy

A

Photon Transducers

36
Q

contain a photosensitive surface that absorbs radiation in the ultraviolet, visible, and near infrared (IR), producing an electric current proportional to the number of photons reaching the transducer

A

. Phototubes and photomultipliers

37
Q

used to calibrate the detector’s response, to amplify the signal from the detector, to remove noise by filtering, or to mathematically transform the signal

A

Signal Processors

38
Q

These have very high excitation energies and do not contribute to absorption in the visible or UV regions

A

Closed shell electrons that are not involved in bonding

39
Q

These also possess too high an excitation energy to contribute to absorption of visible or UV radiation

A

Covalent singlebond electrons

40
Q

These are less tightly held than σ electrons
and can be excited by visible orUVradiation

A

Paired nonbonding outershell electrons

41
Q

These are the most readily excited and are responsible for the majority of visible and UV light absorption.

A

Electrons in π (pi) orbitals

42
Q

formed by head to head overlap of atomic orbitals

A

sigma bond

43
Q

strong and have a high bond energies

A

sigma bond

44
Q

can exist independently

A

sigma bond

45
Q

found in single, double and triple bonds

A

sigma bond

46
Q

the overlapping orbitals can be pure or hybrid

A

sigma bond

47
Q

formed by the side-to-side overlap of atomic orbitals

A

pi bond

48
Q

relatively weak

A

pi bond

49
Q

must exist along the sigma bond

A

pi bond

50
Q

found in double and triple bonds

A

pi bond

51
Q

the overlapping bonds must be unhybridized

A

pi bond

52
Q

The absorbing groups in a molecule

A

chromophores

53
Q

A molecule
containing a chromophore

A

chromogen

54
Q

does not itself absorb radiation, but, if present in a molecule, it can enhance the absorption by a chromophore and/or shift the wavelength of absorption when attached to the chromophore

A

auxochrome

hydroxyl groups, amino groups, and halogens

55
Q

absorption maximum shifted to longer wavelength

A

bathochromic shift

56
Q

absorption maximum shifted to shorter wavelength

A

hypsochromic shift

57
Q

an increase in molar absorptivity

A

hyperchromism

58
Q

a decrease in molar
absorptivity

A

hypochromism

59
Q

The amount of monochromatic radiation absorbed by a sample is described by

A

BEER’S LAW

60
Q

The relationship between the incident radiation and the transmitted radiation

A

TRANSMITTANCE

61
Q

The product of the absorptivity and the molecular weight of the absorbing species is called

A

molar absorptivity

A = εbc

FINALS! ANAMETH LEC (3 decks)

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