  Gas in the million degree range occurs in a variety of astronomical
environments, and it may be the main component of the elusive missing baryons
at low redshift. The NVII ion is found in this material and it has a hyperfine
spin-flip transition with a rest frequency of 53.042 GHz, which can be observed
for z > 0.1, when it is shifted into a suitably transparent radio band. We used
the 42-48 GHz spectrometer on the Green Bank Telescope to search for both
emission and absorption from this NVII transmission. For absorption studies,
3C273, 3C 279, 3C 345, and 4C+39.25 were observed but no feature were seen
above the 5 sigma level. For emission line studies, we observed Abell 1835,
Abell 2390 and the star-forming galaxy PKS 1345+12, but no features were seen
exceeding 5 sigma. We examine whether the strongest emission feature, in Abell
2390 (3.7 sigma), and the strongest absorption feature, toward 4C+39.25 (3.8
sigma), might be expected from theoretical models. The emission feature would
require ~1E10 Msolar of 1E6 K gas, which is inconsistent with X-ray limits for
the O VII Kalpha line, so it is unlikely to be real. The NVII absorption
feature requires a NVII column of 6E16 cm^-2, higher than model predictions by
at least an order of magnitude, which makes it inconsistent with model
expectations. The individual observations were less than 1 hr in length, so for
lengthy observations, we show that NVII absorption line observations can begin
to be useful in in the search for hot intergalactic gas.
