HC18O+
Oxomethylium, formyl cation; 18O isotopolog
Species tag 031506
Version2*
Date of EntryJuly 2024
ContributorH. S. P. Müller

Data of the first entry of Dec. 2004 were replaced by updated ones from
(1) L. Bizzocchi, F. Tonolo, B. M. Giuliano, P. Caselli, M. Melosso, L. Dore, S. Alessandrini, C. Puzzarini, and A. Pietropolli Charmet, 2024, Astrophys. J., 970, Art. No. 26.
The uncertainties in the present calculation are the ones implicitely used in (1), not the ones stated. The calculation should be sufficiently accurate for observational purposes. Increasing caution is advised above 2 THz.
Partition function values given below refer to the ground vibrational state; an estimate of the vibrational partition function of HCO+ may be applied.
The dipole moment is assumed to agree with that of the main isotopic species, see e029507.cat.
Lines Listed47
Frequency / GHz< 4000
Max. J47
log STR0-4.0
log STR1-6.5
Isotope Corr. 
Egy / (cm–1)0.0
 µa / D3.90
 µb / D 
 µc / D 
 A / MHz 
 B / MHz42581.265
 C / MHz 
 Q(1000.)490.5233
 Q(500.0)245.2148
 Q(300.0)147.2114
 Q(225.0)110.4777
 Q(150.0)73.7539
 Q(75.00)37.0402
 Q(37.50)18.6883
 Q(18.75)9.5161
 Q(9.375)4.9361
 Q(5.000)2.8097
 Q(2.725)1.7259
detected in ISM/CSMyes

Database maintained by Holger S. P. Müller and Sven Thorwirth, programming by D. Roth and F. Schlöder