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doppler_width

PURPOSE ^

DOPPLER_WIDTH Doppler line shape width

SYNOPSIS ^

function dd = doppler_width(m,f0,t)

DESCRIPTION ^

 DOPPLER_WIDTH   Doppler line shape width

    The Doppler width is here defined as FWHM/2. That is, half
    width at half maximum (HWHM). More precisely, it is calculated as

       dd = sqrt(log(2)) * f0/c * sqrt(2*R*t/m)

 FORMAT   dd = doppler_width( m, f0, t )
        
 OUT   dd   Doppler width, for each temperature.
 IN    m    Molecular weight. For example 48 for ozone.
       f0   Centre frequency. Only scalar input allowed.
       t    Temperature. Can be a vector.

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

DOWNLOAD ^

doppler_width.m

SOURCE CODE ^

0001 % DOPPLER_WIDTH   Doppler line shape width
0002 %
0003 %    The Doppler width is here defined as FWHM/2. That is, half
0004 %    width at half maximum (HWHM). More precisely, it is calculated as
0005 %
0006 %       dd = sqrt(log(2)) * f0/c * sqrt(2*R*t/m)
0007 %
0008 % FORMAT   dd = doppler_width( m, f0, t )
0009 %
0010 % OUT   dd   Doppler width, for each temperature.
0011 % IN    m    Molecular weight. For example 48 for ozone.
0012 %       f0   Centre frequency. Only scalar input allowed.
0013 %       t    Temperature. Can be a vector.
0014 
0015 % 2006-11-21   Created by Patrick Eriksson.
0016 
0017 
0018 function dd = doppler_width(m,f0,t)
0019 
0020 c = constants( 'SPEED_OF_LIGHT' );
0021 
0022 r = 8.314e3;
0023 
0024 a = sqrt( log(2) ) / c;
0025 
0026 dd = (a*f0) .* sqrt( (2*r/m) * t );

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