Theinfraredmulti-photondissociation（IRMPD）ofaceticanhydridetogeneratestate-selectedCH2hasbeeninvestigatedbyusingtimeandwavelengthresolvedfluorescencetechniques.IthasbeenobservedthatthegenerationofthenascentgroundstateCH2（a1A1）isdelayedbyabout0.6μsrelativetotheonsettimeoftheexcitedCH2（b1B1）.TherelativepopulationofthegroundandexcitedstateCH2andtheonsettimefortheappearanceofthegroundstateCH2havebeenfoundtodependstronglyonCO2laseroutputfluences.TheseresultsappeartohaveastrongbearingonthestructureofthepotentialenergysurfacesoftheintermediateCH2CO.Apossiblephotolysisme-chanismisproposedtoexplaintheseexperimentalresults.
