New spectra of methylene, CH2, in the near infrared region of the singlet b
and system have been obtained. They were detected by laser transient absorp
tion spectroscopy following excimer laser flash photolysis of ketene, CH2CO
, at 308 nm. The new data provide information on the nature and energies of
rotational levels in three vibronic states that lie between approximately
11 500 and 13 000 cm(-1) above the zero point level of the lower, (a) over
tilde (1)A(1), state. Taken together with previous measurements, a fairly c
omplete picture of the vibronic energy levels of CH2 in this region can be
built up. There is generally good agreement with the recent computational s
tudies on the singlet states of CH2, but some evidence for discrepancies fo
r levels with K = 3 and higher near the minimum of the (b) over tilde B-1(1
) potential surface.