2 Usage

A database (.xml file) is required for complete usage of the AmesPAHdbPythonSuite. A few sample dabases are provided with the package installation (located in the resources-directory), however a complete database can be obtained from the NASA Ames PAH IR Spectroscopic Database website. following the Database Downloads instructions.

Below is the example contained in example.py located in the examples-directory and shows how the AmesPAHdbPythonSuite is used to display the (‘stick’) absorption spectrum of coronene (UID=18).

from pkg_resources import resource_filename
from amespahdbpythonsuite.amespahdb import AmesPAHdb

# Read the database.
xml = 'resources/pahdb-theoretical_cutdown.xml'
pahdb = AmesPAHdb(filename=resource_filename('amespahdbpythonsuite', xml), check=False, cache=False)

# Retrieve the transitions from the database for coronene.
transitions = pahdb.gettransitionsbyuid([18])

# Plot the emission 'stick' spectrum.
transitions.plot(show=True)

# Calculate the emission spectrum at the temperature reached
# after absorbing a 6 eV (CGS units) photon.
transitions.cascade(6 * 1.603e-12, multiprocessing=False)

# Plot the emission 'stick' spectrum at that temperature.
transitions.plot(show=True)

# Convolve the bands with a Gaussian with FWHM of 15 /cm.
convolved = transitions.convolve(fwhm=15.0, gaussian=True, multiprocessing=False)

convolved.plot(show=True)