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instrumid > 2 > Flashcards

2 Flashcards

1
Q

used to measure concentration by detecting absorption of electromagnetic radiation by atoms rather than by
molecules.

A

ATOMIC ABSORPTION SPECTROPHOTOMETERY (AAS)

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2
Q

usual light source of AAS, known as a

A

hallow-cathode lamp

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3
Q

consists of an evacuated gastight chamber containing an
anode

A

hallow-cathode lamp

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4
Q

has anode in a gastight chamber/cylindrical

A

Hallow Cathode lamp

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5
Q

Hallow Cathode lamp GASES

A

Helium and Argon

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6
Q

Metal knocks atoms off to be excited upon excitation they return to ground state =

A

LIGHT EMISSION

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7
Q

measured by Copper hollow cathode lamp

A

Cu

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8
Q

a conductor that is used to make contact with a nonmetallic part of a circuit.

A

Electrode

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9
Q

Becomes the new light source for the AAS

A

Electrode

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10
Q

-filled argon excites an element to emit a spectrum

A

The bulb

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11
Q

is alternative of a cuvette

A

FLAME

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12
Q

is a long and narrow slit, to permit a longer path length for absorption of incident radiation to occur

A

The burner

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13
Q

It is used to measure light emitted by excited atoms.

A

Flame Emission Photometry

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14
Q

It is used primarily to determine concentration of Na+, K+, or Li+. The
sample solution is aspirated into the flame.

A

FEP

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15
Q

ELECTRICAL SIGNAL PROPORTIONAL TO THE CONCENTRATION OF ATOMS (FEP)

A

T

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16
Q

•is subjected to Fourier transformation, which calculates the contributions of the constituent frequencies and plots the spectrum as intensity versus wavelength, or wavenumbers (cm-1), as is commonly used in infrared spectroscopy.

A

INTERFEROGRAM

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17
Q

•One of the major advantages of Fourier transform infrared (FTIR) spectroscopy is that ti can give detailed qualitative and quantitative chemical information without destroying the sample.
•In most cases, the samples used for FTIR spectroscopic investigations can be completely recovered and used for further analysis elsewhere.

A

Advantages

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18
Q

•include cases when samples are too concentrated, practically absorbing all infrared radiation, and thus must be diluted by mixing with infrared transparent diluters, such as KBr for diffuse reflectance measurements.

A

EXCEPTION

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19
Q

TRANSMISSION SAMPLES CAN BE:

A

GAS, LIQUIDS OR SOLIDS

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20
Q

TRANSMISSION Advantages:

A

• Simple, practical and superior speed of 100spectra/second

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21
Q

Transmission Disadvantages:

A

•Window cleaning
•Window must be made of RI transparent material

22
Q

is the oldest and perhaps most straightforward infrared spectroscopic method: the sample is simply placed
in the beam path of the infrared radiation.

A

Transmission

23
Q

are based on the interactions of reflected infrared light with the sample. These methods are often used instead of transmission techniques when transmission is too difficult to implement, or when only specific areas of the sample need to be analyzed, such as surfaces or thin layers.

A

Reflectance methods

24
Q

• is the possibility to investigate the spatial distribution of chemical changes and sample heterogeneity, and to follow reaction fronts and reactions at certain sites, as wel as precise sampling, such as when only measuring a certain area ni a sample.
• highest achievable spatial resolution:

A

MICROSPECTROSCOPY

25
Q

are capable of recording images at diffraction limited spatial resolution

A

Modern FPA detectors

26
Q

the spreading of waves around obstacles

A

diffraction

27
Q

MICROSPECTROSCOPY SAMPLES CAN BE:

A

solids or liquids, suspensions or colloids

28
Q

MICROSPECTROSCOPY Analysis can be done on

A

single samples, multiple spotson a single sample or on multiple samples

29
Q

refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region.

A

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis)

30
Q

In this region of the electromagnetic spectrum, molecules undergo electronic transitions. This technique is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state.

A

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis)

31
Q

• is routinely used ni analytical chemistry for the quantitative determination of different analytes, such as transition metal ions, highly conjugated organic compounds, and biological macromolecules.

A

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis)

32
Q

• is routinely used ni analytical chemistry for the quantitative determination of different analytes, such as transition metal ions, highly conjugated organic compounds, and biological macromolecules.

A

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis)

33
Q

may be used as a detector for HPLC

A

UV/Vis spectrophotometer

34
Q

• The presence of an analyte gives a response assumed to be proportional to the concentration.

A

UV-VIS

35
Q
  • most common type of photon detector and provides an amplified signal nearly Imillion times larger than phototube counterparts
A

PMTs

36
Q

Each dynodes has_____ higher than phototubes

A

90V

37
Q

Upon striking each dynodes they interact with each other and cause_____ ___.

A

photoelectron emission

38
Q

PMT has several electrodes called

A

dynodes

39
Q

-consists of a flat copper or iron electrode upon which is deposited a layer of semiconductor (coated with transparent metallic film of gold or silver) material such as selenium When the radiation of sufficient energy that reaches the semiconductor, covalent bonds are broken with the result that conduction electrons and the holes are formed.

A

PVT

40
Q

The result is an electrical current of a magnitude that is proportional to the number of photons that strike the semiconductor surface and a photocurrent that is directly proportional to the intensity of radiation that strikes the cells.

A

Pvt

41
Q

● The photoemissive material that tends to emit electrons when it is irradiated———> by the addition of a potential applied across the electrode–> electrons flow to the wire anode —-> creates and generates photocurrent of about 1/10 greater than PVT

A

Vacuum phototubes

42
Q

The number of electrons ejected from a photoemissive surface is ______ to the radiant power of beam that strikes the surface

A

DIRECTLY PROPORTIONAL

43
Q

● Has positively and negatively charged semiconductive materials and a power supply to connect the poles

A

Silicon Diode transducers

44
Q

● A silicon chip contains also electric circuitry that determines the electrical output from each of the photosensitive elements.

A

Multi channel photon transducers

45
Q
  • histrogram profile output
A

Photo iodide arrays

46
Q
  • alternative to photo iodides, photon-striking IC semiconductor material
A

Charge injection Devices

47
Q
  • all of the charge packets are moved “in-step” along the array row from one pixel to the next, as in a bucket chain.
A

Charge coupled Devices

48
Q

A device that rectifies (or the reverse) alters the phase of signal, filters to remove
unwanted components.

A

Data Readout

49
Q
  • change indicator (of the variables in its environment such as pressure, temperature, electrical charge, electromagnetic radiation, nuclear radiation, particulates or molecules).
A

Detectors

50
Q
  • (current producer)devices that convert information in nonelectrical domains and the converse. It includes photo iodides, photomultipliers and those that produce current
A

Transducer

51
Q

-chemical species monitoring (electrodes).

A

sensors

instrumid (3 decks)

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