Optical spectrometry:
In optical spectrometry, the source of the spectrometer is the device from which the radiation is emitted. This may be a flame or plasma source.

Mass spectrometry:
The source is the device within the mass spectrometer in which ionization of sample molecules occurs. The source may be under vacuum, or it can operate at atmospheric pressure. A chromatographic method may interface with the source, or samples may be introduced via a probe or an automated sample introduction system. Ions are accelerated out of the source into the mass analyzer of the instrument.

The term "source" was found in the following pages:

Instrument database: Hitachi - Science & Technology - H-9500 Transmission Electron Microscope
Instrument database: PerkinElmer Inc. - Spectrum GX Optica System
Instrument database: PerkinElmer Inc. - Flexar SQ 300 MS
Instrument database: Sedico Ltd. - Phoenix-2200DPCV UV/Vis Spectrophotometer
Material database: National Institute for Environmental Studies (NIES) - NIES CRM 10 a: Rice Flour-Unpolished, Low Level Cadmium
Instrument database: Analytik Jena AG - Mercur - Atomic fluorescence spectrometer for mercury determination
Journals database: Archives of Orthopaedic and Trauma Surgery
EVISA's web portal | EVISA's News
New research results suggest that mercury hotspots in the northeastern US are home made | EVISA's News
Instrument database: Agilent Technologies Inc. - 7010 Series Triple Quadrupole GC/MS
Journals database: ICP Information Newsletter
Instrument database: Applied Biosystems - Q TRAP® LC/MS/MS System
Instrument database: Shimadzu Europe - IRAffinity-1S - Fourier Transform Infrared Spectrophotometer
Journals database: Journal of the American Dental Association
Link database: Chemical Fact Sheet: Cobalt
Company database: Endocrine Society
Instrument database: PerkinElmer Inc. - Clarus 600 Gas Chromatograph/Mass Spectrometers
Journals database: Studies in Conservation
Instrument database: Bruker Daltonics - micrOTOF-Q
Flow-injection inductively coupled plasma mass spectrometry for speciation analysis | EVISA's News