Absorption spectroscopy of singlet CH2 near 11 200 cm(-1)

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.