Absorption spectroscopy of singlet CH₂ near 11 200 cm^-1

New spectra of methylene, CH₂, in the near infrared region of the singlet band system have been obtained. They were detected by laser transient absorption 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, ã ¹A₁, state. Taken together with previous measurements, a fairly complete picture of the vibronic energy levels of CH₂ in this region can be built up. There is generally good agreement with the recent computational studies on the singlet states of CH₂. but some evidence for discrepancies for levels with K = 3 and higher near the minimum of the b̃ ¹B₁ potential surface.