Why few research on 140GHz band communication?

recently i read some papers about terahertz communications and most of them work at 280-310GHz band. as we know, 140GHz is also at the absorption valley of the atmosphere. are there any IEEE or ITU standard about 140GHz band? why few research about 140GHz band communications? thanks for your discussion

Actually the absorption of Oxygen happen at 120GHz (Lamda=0.25cm), and not at 140GHz.
https://www.researchgate.net/profile...3K-and-the.png
However, at 120GHz the magnitude of Oxygen absorption coefficient (attenuation) is smaller compared to 60GHz.

There are studies regarding 120GHz frequency band:
https://www.researchgate.net/publica...a_Transmission