Cross-Sections

The method is described in: C. Hill, S. N. Yurchenko, J. Tennyson, “Temperature-dependent molecular absorption cross sections for exoplanets and other atmospheres”, Icarus, 226, 1673-1677 (2013). See the paper here.

Gaussian profile

Example (HWHM is the half-width at half-maximum):

Temperature  2000.0
Range 0.0  12000.0

Npoints 200001
absorption
Gaussian
HWHM 0.5 (cm-1)
threshold 1e-40 (to skip weak lines)

output abs_gauss_0.5_T2000.0

States  "../all/ch4-50.states-all"

Transitions
 a-03000.dat
 a-03100.dat
 a-03200.dat
 a-03300.dat
 a-03400.dat
 a-03500.dat
 a-03600.dat
 a-03700.dat
 a-03800.dat
 a-03900.dat
end

Doppler profile

Doppler is the effective mass of the molecule in amu.

Example:

Temperature  1500.0
Range 0.0  12000.0
Npoints 200001

emission
doppl
mass 16.0313

output dop_emiss_1500.0
States ch4-50.states-all

Transitions a-02100.dat

Lorentzian profile

Here b is the normalization factor.

Example:

Temperature  300
Range 0.0  10000.0
Npoints 10001

absorption
Loren
HWHM 0.1 (cm-1)

output abs_lor_0.1_T300.0

States  NaH.states

Transitions NiH.trans

Stick spectrum

Example:

(ScH stick spectrum)
Temperature 1500.0
Range 0.  16000.0

Npoints 16001

absorption
stick
threshold 1e-29

output ScH_1500K_stick
States       ScH.states
Transitions  ScH.trans

bin

is to produce average intensity per the wavenumber or wavelength interval as defined by Range/(Npoints-1). The wavelength is invoked by adding um to the range values.

Example:

(ScH bin spectrum)
Temperature 1500.0
Range 0.  16000.0

Npoints 16001

absorption
bin

output ScH_1500K_bin_stick
States       ScH.states
Transitions  ScH.trans

or:

(ScH bin spectrum)
Temperature 1500.0
Range 1.  100.0 um (or micron)

Box

Is to plot the maximal transition intensity per wavenumber interval, which is a cheaper alternative for the stick spectrum

Example:

(ScH box spectrum)
Temperature 1500.0
Range 0.  16000.0

Npoints 16001

abundance 0.97

absorption
box
threshold 1e-29

output ScH_1500K_box_stick
States       ScH.states
Transitions  ScH.trans

Line-width cut-offs

A line width cut-off can be defined using offset or line-cutoff

offset 25 (cm-1)
line-cutoff 25 (cm-1)

where the offset value is in wavenumbers (cm-1). The default value is 25 cm-1. Alternatively, one can define the cut-off in terms of the HWHM as follows:

offset 50 HWHM

multi-grid

A multi-grid with regions of different resolutions can be defined using the following grid section:

grid
  Range   0    100   Npoints 10000 offset 10
  Range 100   1000  Npoints 1000  offset 25
  Range 1000 10000  Npoints 100
end

The maximal number of sub-grids is 100. Currently this option only works with simple sampling-type profiles, such as Voigt, Doppler Sampling, Gaussian Sampling or Bin. The latter is commonly used to generate super-lines. offset or line-cutoff is an optional keyword to allow region-dependent cutoffs for line profiles. If undefined, the value of the global keyword offset the corresponding default value (25 cm-1) is used.

gf line list

A stick spectrum is produced with the gf-factors in place of the Einstein coefficients. Here is the example for the VALD format, where the columns are the wavelength in Angstrom, the lower state energy in eV, log10(gf), 0.0, the statistical weight 2J’+1 (upper state J’) and zero.

temperature 5000
Range 100.  16000.0

gf
vald
threshold 1e-29

output ScH_gf
States       ScH.states
Transitions  ScH.trans