LAB spectrophotometry Flashcards
factors affecting light source
range spectral distribution within the range source of radiant production stability of radiant energy temperature
two light sources
incandescent lamps
LASER
most common light source for visible region and near infrared
tungsten lamp
two forms of tungsten lamps
tungsten iodide
incandescent tungsten
inserted between lamp and sample for absorption of infrared radiation
heat absorbing filter
increases lifetime of tungsten lamp
iodine or bromine vapor
4 lamps used for measurement in the UV region
deuterium discharge lamp
hydrogen lamp
mercury-arc lamp
xenon lamp
deuterium discharge lamps emit continuous spectra down to _____
165 nm
has less stable and shorter life that deuterium discharge
hydrogen lamp
three types of mercury arc lamp
low pressure mercury arc lamp
medium pressure mercury arc lamp
high pressure mercury arc lamp
emits a sharp line for UV and visible regions
low pressure mercury arc lamp
used for calibration purposes only
low pressure emrcury arc lamp
has a continuum from UV to mid visible region
medium and high pressure mercury arc lamp
meaning of LASER
light amplification by stimulated emission of radiation
laser characteristics
extremely intense
focused
non divergent light
wavelength of laser:
argon fluoride
193 nm/ 248 nm
wavelength of laser:
helium cadmium
325 nm / 442 nm
wavelength of laser:
nitrogen
337 nm
wavelength of laser:
argon blue
488 nm
wavelength of laser:
argon (green)
514 nm
wavelength of laser:
helium- neon (green)
543 nm
wavelength of laser: helium neon (red)
633 nm
minimizes and prevents entry of stray light into monochromator
entrance slit
isolates a specific wavelength of light
monochromator
monochromators are characterized with a specific : ?
bandpass
range of wavelengths permitted to impinge on the sample
bandpass
what is bandpass
width at more than half the maximum transmittance
three kinds of monochromators
filters
prisms
gratings