Anomalous absorption in thioformaldehyde

Absorption against the Cosmic Microwave Background (CMB), called the anomalous absorption, is an unusual phenomenon. The transition 111–110 at 4.829 GHz of formaldehyde (H2CO) was the first one showing the anomalous absorption. The c-C3H2 is the second molecule showing anomalous absorption through its transition 220–211 at 21.590 GHz. Structure of thioformaldehyde (H2CS) is very similar to that of the H2CO. Therefore, we have investigated about the physical conditions under which the transition 111– 110 at 1.0465 GHz of H2CS would be found in anomalous absorption in cool cosmic objects. As in case of H2CO, the anomalous absorption of 111–110 of H2CS is found sensitive to the relative collisional rates and it requires that the collisional rate for the transition 111–211 must be smaller than that for the transition 110–212.