🐛 Describe the bug

from radis import calc_spectrum

s_NOp = calc_spectrum(
    wavenum_min=2380,
    wavenum_max=2400,
    mole_fraction={'NO+':1},
    isotope=1,
    Tgas=2000,
    pressure=1,
)

Does not produce an NO+ spectrum because the name NO is converted to NO_II. Probably a feature coded when we added the atomic databases.

💡 Possible solutions

Prevent this conversion with molecules

🎲 Radis version

0.16.3

💻 Operating system

Windows