Chapter 5: Light and Matter

Fourier Transform

Fourier Transform

The wavelengths of light that are absorbed by the sample are sorted out and displayed as either a function of absorbance or transmittance.

Monochromator

A device that selects one particular wavelength to be exposed to the sample.

Frequency

The number of waves that passes a given point in 1s.

UV visible spectrophotometry

________ can also be used to determine the amount of a substance in a mixture.

Gas molecules

________ are ionized prior to entering the quadrupole zone, so that they have a charge and can be isolated in the tuned quadrupole zone.

Atomic Absorption Spectroscopy

Substances are analyzed in the vapor phase.

Diffuse Reflectance

Uses a set of mirrors that direct the IR source light at the sample at an oblique angle to the surface of the material, which then absorbs some of the light.

Demodulation

Radio waves and the carrier wave are separated.

AE

________ is used when the material being analyzed has a large number of elements that are being analyzed such as an unknown metallic material or sometimes an automotive paint chip.

Modulation

________ can be accomplished using either amplitude (AM) or frequency (FM)

Fluorescence

This occurs when a substance absorbs energy and then emits it in the form of visible light.

IR Spectroscopy

It is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection.

Orbital

An energy level where an electron resides.

Electromagnetic Radiation

It refers to the various forms of energy in the form of waves.

photon

A(n) ________ that causes electron promotion in atoms and molecules is in the UV /visible region of the electromagnetic spectrum.

IR Microspectrophotometry

Enables an evaluation of colors to be made objectively using UV- visible transmittance profiles.

Inductively Coupled Plasma Mass Spectrometry

In ________, the glass is digested and is transformed into an aerosol by a nebulizer that breaks up the sample into very small droplets.

Raman Spectroscopy

A molecular spectroscopic technique that utilizes the interaction of light with matter to gain insight into a material's make up or characteristics, like FTIR.

Electron Impact

An ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions.

Raman spectrum

The ________ is measured as the chemical shifts of the emitted photons- which is the difference in energy between the incident photon and the inelastically scattered emitted photon.

mass spectrometer

A(n) ________ can be designed as a detector for a gas chromatograph or liquid chromatograph.

Magnetic Sector Mass Spectrometry

The ions are accelerated through a curved magnetic field toward the detector.

UV visible radiation

When a substance is exposed to ________, it will absorb certain photons of particular energy.

IR detectors

________ are usually some type of thermocouple- a device that converts heat into electricity.

Transmission Spectrum

TThe computer stores the wavelength and corresponding electric current and then, when the entire spectrum has been obtained, will construct a graph of wavelength versus intensity of transmitted light.

AA spectroscopy

________ is very sensitive but the analyte must be vaporized and a separate experiment must be done for each element.

Modulation

Radio waves are transported through the air to the radio receiver by a carrier wave.

Raman spectroscopy

________ is routinely used in the analysis of drugs, paints, inks and dyes, and fibers.

IR spectrophotometry

________ is a practically universal technique for the analysis of evidence.

electromagnetic radiation

When a substance is exposed to ________, it undergoes changes that may or may not be reversible and which depend upon the energy of the radiation.

Electromagnetic Radiation

It refers to the various forms of energy in the form of waves

Wavelength

The distance between corresponding points on two adjacent waves

Frequency

The number of waves that passes a given point in 1s

wavenumbers

Frequency can also be expressed in other units, called __________.

Photons

tiny packets of energy

Infrared

When absorbed by matter, this type of light causes bonds between atoms in a molecule to vibrate like two weights on either end of a spring

Radio waves

These have very long wavelengths and thus very low frequencies and relatively little energy

Monochromator

Adevice that selects one particular wavelength to be exposed to the sample

Absorption Spectrum

The computer can also convert this to the wavelength versus amount of light absorbed by the sample

Reflectance spectra

the visible region of the electromagnetic spectrum holds information that defines product color

Diffuse Reflectance

Uses a set of mirrors that direct the IR source light at the sample at an oblique angle to the surface of the material, which then absorbs some of the light

Attenuated Total Reflectance (ATR)

Uses a special crystal that is brought into direct contact with the sample

Elastic energy

the energy of the scattered photon is the same as that of the incident or absorbed photon

Inelastic energy

the energy of the scattered photon can be greater or less than that of the incident one

Electron Impact

an ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions

Chemical Ionization

relies on gas-phase chemical reactions that take place between the analyte of interest and ions generated from a reagent gas

Laser Desorption mass spectrometry

uses a laser to ionize the analyte

Matrix Assisted Laser Desorption Ionization (MALDI)

The matrix absorbs the laser energy and transfers it to the analyte

Magnetic Sector Mass Spectrometry

the ions are accelerated through a curved magnetic field toward the detector

Quadrupole Mass Spectrometry

separate ions by their mass and pass them to a detector, where they are counted

Time-of-Flight Mass Spectrometry

the ions are accelerated by a magnetic field of known strength

Atomic Absorption Spectroscopy (AAS)

substances are analyzed in the vapor phase

Atomic Emission Spectroscopy (AES)

this is not as sensitive as AA and it is analytical technique used for the quantification of metal atoms by measuring the intensity of light emitted by the atoms in excited states