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Chem/Phys Exam 4 > Spectrometry > Flashcards

Flashcards in Spectrometry Deck (29)
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1
Q

Qualitative analysis

A
  • Identity or properties of the drug or substance

- Separation, isolation or purification required in most cases, but not all

2
Q

Quantitative analysis

A

How much substance is present

3
Q

Frequency

A
  • How quickly light gets to you
  • hertz (Hz) (1 cycle/sec)
  • kilohertz (1000 cycle/sec)
4
Q

Wavelength

A

distance in meters between peak and trough

5
Q

Electromagnetic energy properties

A

waves, frequency, and wavelength

6
Q

1 micron = X meters

A

10^-6 meters

7
Q

1 nanometer = X meters

A

10^-9 meters (1 m)

8
Q

1 Angstrom = X meters

A

10^-10 meters

9
Q

Wavelengths of the visible part of the spectrum in nanometers

A

390 - 750 nm

10
Q

Wavelengths of the visible part of the spectrum in angstroms

A

4300 A (violet) - 7000 A (red)

11
Q

The shorter the wavelength, the _____ the frequency and the ____ higher the energy

A

The shorter the wavelength, the greater the frequency and the higher the energy.
Short wavelength = high energy = blue/violet light

12
Q

As molecules are exposed to light (or other energy) they can absorb energy by:

A
  • electromagnetic excitation

- molecular vibrations

13
Q

electromagenetic excitation

A

electrons in the molecule goes from a low energy state to a higher energy state)

14
Q

molecular vibrations

A

each compound has natural vibration frequency

Simplest molecule of 2 atoms bound together, we can excite the electrons and they can vibrate, stretch, and bend

15
Q

After a molecule is excited it can release the energy in various forms

A
  • heat (most common!)
  • rupture of the molecule (washing a red shirt fades to pink when hung in the sun to dry)
  • re-emission of energy as altered electromagnetic energy (fluorescence)
16
Q

The useful parts of the spectrum are:

A
  • UV
  • visible
  • infrared radiation
17
Q

UV and visible absorption

A

electronic absorption (electrons in molecules are excited to a higher energy state)

18
Q

Infrared absorption

A

due to vibrational energies of a molecule: bending, stretching, and rotation (cannot see infrared)

19
Q

chromophores

A

Most molecules have chromophores that absorb light. Chromophores may be certain molecular groups, such as phenyl groups or double bonds.

20
Q

chromosphere

A

Parts of the molecule that allow it to absorb light/radiation.
Ie: phenyl group on a drug can be analyzed by UV radiation

21
Q

Basic Instrument Components of a Heme Oximeter

A

1) Energy source to produce, radiation (a deuterium [uv] or tungsten lamp [visible])
2) A system to select limited part of the spectrum (prism or grating)
3) Sample chamber
4) Detector

22
Q

prisms

A

Prisms slow down wavelengths of different waves of white light and reflect the colors of the rainbow

23
Q

Detector or Photomultiplier Tube

A

converts light energy to electrical energy

24
Q

For any compound, absorbance is proportional to:

A
  • thickness of the cuvette (or light path)

- the concentration of the compound

25
Q

absorption

A
  • Absorption is dependent on the probability of radiation causing an electron being excited in the substance.
  • If coefficient is small, substance poorly absorbs light
26
Q

Light intensity across a cell

A

is an exponential decay

27
Q

Light intensity calculation

A

I=Ioe-kL

I = emergent light
Io = incident light
k = a constant
L = length of light path
28
Q

absorbance

A

log of the ratio of incident to emergent light

Io/I

29
Q

absorbance is referred to as

A

absorbance, extinction, or optical density