{'fraction_non_alphanumeric': 0.01991465149359886, 'fraction_numerical': 0.00995732574679943, 'mean_word_length': 4.818181818181818, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Low-energy electron collisions with C2 using the R-matrix method

Calculations are presented for the bound and continuum states of the C−2 system using the polyatomic version of the UK molecular R-matrix code. The calculations, based on a 26-state close-coupling expansion, show the presence of three bound doublet states of C−2 and a quartet state that only becomes bound at large internuclear separation. A number of resonance states are found and their behaviour as a function of the C2 bond length is studied. Cross sections for electron impact electronic excitation are presented with particular emphasis on excitation of the d 3Πg state which is responsible for the well-known Swan emission bands.