Spectroscopy: Chapter 11 Flashcards
What is a mass spectrometer?
an instrument that produces ions and separates them according to their mass/charge ratio
What are the basic instrumental components of mass spectrometers?
- Inlet System
- Ionization Source
- Mass Analyzer
- Ion Transducer
- Vaccum system
- Signal processor
What is the most common transducer used for Mass Spectrometry?
Electron multipliers
What are the 3 types of Transducers used for Mass Spectrometry?
- Electron Multipliers
- The Faraday Cup
- Array Transducers
What are the two types of Electron Multipliers?
- Discrete-dynode electron multiplier
- Continous-dynode electron multiplier
what does ICPMS stand for?
Inductively Coupled Plasma Mass Spectrometry
What are charateristics of ICPMS that makes it one of the most important techniques for elemental analysis?
- low-detection limits for most elements
- high degree of selectivity
- good precision and accuracy
What does an ICP torch serve as in ICPMS?
an atomizer and ionizer.
when dealing with multielemental analysis of rare earth elements and other heavy metals, what is the advantage of using an atomic mass spectra compared to an optical emission spectra?
they are easier to interpret, optical emission spectra would be very complex to interpret.
Why is an internal standard usually used for the standards and unknowns with ICPMS?
The internal standard is a substance that is inserted in fixed amounts that responds to uncontrollable variables.
By using the ratio of the [analyte signal/internal standard] then analytical reading is found
What is the difference between exact mass and nominal mass?
a nominal mass is represented as a whole number while an exact mass has decimal places after the whole number
Define a Fragmentation Pattern
Two molecules with the same molecular ion might have different fragmentation
What are the ordinate and the abscissa of an ordinary atomic mass spectrum?
The ordinate (y-axis ) is usually the relative abundances or intensities of the ions.
The abscissa (x-axis) is usually the mass-to-charge ratio
How are lasers used as a means for sampling solids for ICPMS?
solid sample is struck by the laser beam in order to vaporize it, the it is carried into the ICP torch where atomization and vaporization occurs.
What types of mass spectrometers are used in ICPMS?
- Quadrupole mass analyzers
- Time of flight mass spectrometers
- Double focusing mass spectrometers
**homework question.
