Is a neutral $\ce{Hg2}$ molecule possible, as a gas under extremely low (partial) pressures? What is the enthalpy of formation or similar?

It is my impression that usual mercury vapors are monatomic? I think it is well-known that a dimer ion $\ce{Hg2^{2+}}$ exists under some conditions.

Somewhat related threads: [Is it possible to have a diatomic molecule of sodium in gaseous state?](https://chemistry.stackexchange.com/questions/32686/) and [Which elements can be diatomic?](https://chemistry.stackexchange.com/questions/32705/)