The Basics

This simulator plots linestrength as a function of temperature, including any air-induced pressure shift.

You can run up to 3 simulations, each with 3 species (for a total of 9), before you must clear the plot.

Up to 10000 lines will be plotted for each species in each simulation. If more than 10000 lines are returned, reduce your search window or increase your minimum linestrength.

Use the left and right arrows to jump to the next line. The center frequency ν, linestrength S, and E'' are displayed in the top left

Please don't hesitate to get in touch using the 'Contact' link in the bottom right!

The Details

Linestrengths are given in units of cm^-2/atm such that α(ν) = S(T)*P*χ_abs*L*φ(ν) where P is the total pressure of the gas in atm, χ_abs is the absorbing species mole fraction, L is the path length in cm, and φ is the lineshape function in cm.

To convert cm^-2/atm to HITRAN units (cm^-1/molecule-cm²), multiply by T/7.34e-21 with temperature in K.

The frequency of each transition is calculated at the specified temperature and pressure using the air-pressure-shift coefficients given in HITRAN or HITEMP at 296 K.

Therefore, this calculation is performed assuming the absorbing species is dilute in air.

The air-pressure-shift coefficients are estimated at the specified temperature using the power-law relationship with a temperature exponent of 0.96.

The Basics

This simulator plots linestrength as a function of temperature.

You can run up to 3 simulations, each with 3 species (for a total of 9), before you must clear the plot.

Up to 15000 lines will be plotted for each species in each simulation. If more than 15000 lines are returned, reduce your search window or increase your minimum linestrength.

All wavelengths and frequencies correspond to vacuum values.

Use the left and right arrows to jump to the next line. The center frequency ν_o, linestrength S, and lower- and upper-state energies E'' and E', and degeneracies are displayed in the top left

Please don't hesitate to get in touch using the 'Contact' link in the bottom right!

The Details

Linestrengths are given in units of cm^-2/atm such that α(ν) = S(T)*P*χ_abs*L*φ(ν) where P is the total pressure of the gas in atm, χ_abs is the absorbing species mole fraction, L is the path length in cm, and φ is the lineshape function in cm.

To convert cm^-2/atm to HITRAN units (cm^-1/molecule-cm²), multiply by T/7.34e-21 with temperature in K.

For NIST ASD simulations, the linestrength of each transition is calculated according to the Einstein-A coefficient given by NIST, the degeneracies of the lower- and upper electronic states given by NIST, and the user-specified electronic and kinetic temperatures. The location of transitions without Einstein-A coefficients in NIST’s ASD are displayed in the Survey, but there linestrength is indicated (in the top left) as 0.

If either the upper or lower state degeneracy (but not both) of a transition are not given in NIST’s ASD, the missing value is assigned its given counterpart.

Please consult the NIST ASD website for proper bibliographic sources and references.