Strengths of rotational lines from H2CC molecule: Addressing tentative detection

Though H2C, H2CCC, H2CCCC, H2CCO, H2CO, H2CS molecules have been identified in cool interstellar clouds, identification of H2CC is still awaited. Formation of H2CC in the interstellar medium is quite probable as the cosmic abundance of carbon is 20 times larger than that of the sulphur, and the molecule H2CS has already been identified in the interstellar medium. To our knowledge, no laboratory study for H2CC is available in literature. Physical conditions in the interstellar medium are quite different as compared to those in a terrestrial laboratory. Using the rotational and centrifugal distortion constants for H2CC, we have calculated the energies of rotational levels and the strengths of lines between the levels up to 270 cm−1. We have found that 88 and 87 lines of ortho-H2CC and para-H2CC, respectively have Einstein A-coefficient larger than 10−5 s−1. These lines may help in the identification of H2CC in the interstellar medium. Tentative detection of H2CC has been addressed.