The goal is to click on a dip caused by a known absorption line
. That's why it's important to use a prominent A-type star for calibration.
Another feature is a strong absorption line
of Mg II at 4482 [Angstrom] (Figure 3).
It will be capable of detecting and measuring the mass of the WHIM by observing oxygen and other elemental absorption lines
by foreground clouds in the spectra of quasars with orders of magnitude more sensitivity and better resolution than Chandra and XMM-Newton.
where the quantity A([bar.v] = ln([PHI]([bar.v])/[[PHI].sub.0]([bar.v])) is the spectral absorbance (Naperian), in certain cases (see, e.g., http://goldbook.iupac.org/A00028.html) also called extinction, and [A.sub.line] is the spectrally integrated area of the absorption line
. Using (2) the species amount fraction can be derived from spectroscopic measurements as pointed out in previous publications .
FTIR (450-4000 [cm.sup.-1]) and Raman (95-3000 [cm.sup.-1]) spectra have been presented with different absorption lines
and their association with corresponding vibrational modes on the basis of DFT calculations.
For the integrated line spectroscopy the magnitude to be measured is the area under a few absorption lines
Since the late 1960s, observers have been checking to see whether the spacings between the absorption lines
in quasar spectra differ slightly from those observed in laboratory experiments.
Note that there are absorption lines
from various atmospheric gasses, but there are major transmission widows in the near-, mid-, and far-IR ranges.
Furthermore, infrared DIAL systems are preferred because they are highly sensitive to the laser energy, are relatively eye safe, and more importantly, are in the spectral range where most molecular-specific absorption lines
occur.|3~ Of the available infrared lasers, C|O.sub.2~ lasers are the best suited for long path atmospheric monitoring because they have the highest efficiencies and powers, are easily tuned, and cover the 9.2 to 10.9 ||micro~meter~ range, which is rich in molecular-specific spectra.
Light from a star surrounded by a cloud of gas often shows absorption lines
produced when starlight of a specific energy is absorbed by atoms in the gas cloud.
There were some hints that this couldn't be the case - for example, early spectrometry (looking at the wavelengths of light visible in the sun) showed that we could identify the elements in the sun, by looking at the absorption lines