Spectral resolution

<h2 id="doppler-effect">Doppler effect</h2>
<p>The spectral resolution can also be expressed in terms of physical quantities, such as velocity; then it describes the difference between velocities 
  
    
      
        Δ
        v
      
    
    {\displaystyle \Delta v}
  
 that can be distinguished through the <a href="/facts/Doppler_effect/bzrK1BKf">Doppler effect</a>. Then, the resolution is 
  
    
      
        Δ
        v
      
    
    {\displaystyle \Delta v}
  
 and the resolving power is

R
        =
        
          
            c
            
              Δ
              v
            
          
        
        ,
      
    
    {\displaystyle R={\frac {c}{\Delta v}},}

where 
  
    
      
        c
      
    
    {\displaystyle c}
  
 is the <a href="/facts/Speed_of_light/sKSQwdNx">speed of light</a>.  The STIS example above then has a spectral resolution of 51 <a href="/facts/Kilometres_per_second/hSEkho3J">km/s</a>.
</p>
<h2 id="iupac-definition">IUPAC definition</h2>
<p><a href="/facts/International_Union_of_Pure_and_Applied_Chemistry/2AV6myCK">IUPAC</a> defines resolution in optical spectroscopy as the minimum wavenumber, wavelength or frequency difference between two lines in a spectrum that can be distinguished.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Resolving power, <i>R</i>, is given by the transition wavenumber, wavelength or frequency, divided by the resolution.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Angular_resolution/wJarPBWF">Angular resolution</a></li>
<li><a href="/facts/Resolution_(mass_spectrometry)/3kUVcXwg">Resolution (mass spectrometry)</a></li></ul>

<h2 id="further-reading">Further reading</h2>
<ul><li>Kim Quijano, J., et al. (2003), <i>STIS Instrument Handbook</i>, Version 7.0, (Baltimore: STScI)</li>
<li>Frank L. Pedrotti, S.J. (2007), <i>Introduction to optics</i>, 3rd version, (San Francisco)</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>- CRIRES Instrument page at ESO <a href="http://www.eso.org/instruments/crires/" target="_blank">http://www.eso.org/instruments/crires/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "resolution in optical spectroscopy". doi:10.1351/goldbook.R05319 <a href="/wiki/International_Union_of_Pure_and_Applied_Chemistry" target="_blank">/wiki/International_Union_of_Pure_and_Applied_Chemistry</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "resolving power, R, in optical spectroscopy". doi:10.1351/goldbook.R05322 <a href="/wiki/International_Union_of_Pure_and_Applied_Chemistry" target="_blank">/wiki/International_Union_of_Pure_and_Applied_Chemistry</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

Spectral resolution open-in-new

Spectral resolution