The Mid-Infrared Laser Spectroscopy Of Hydroxyacetone

Hydroxyacetone,CH3COCH2OH,is a very important molecule in astrophysical area.It exhibits the next level of molecular complexity in species that have carbon backbones with adjacent oxygen atoms.In the laboratory,hydroxyacetone is an important starting material in the organic synthesis of chemical compound such as acetals and ketals.However,it has very complex spectrum owing to the presence of an internal methyl group rotor and internal hydrogen bond.The internal methyl group rotor leads to torsional energy levels because of this internal rotation and each level can split into two sublevels,characterized by the A-species(? = 0)and E-species(? = ± 1).In this thesis,a self-built pulsed supersonic molecular beam spectroscopy experimental platform is described.The light source is distributed feedback quantum cascade laser(DFB-QCL)and its output range is 1285.0-1290.5 cm-1.Firstly,the performance of the components is introduced.A variety of experimental devices including Herriott absorption cell are tested.Secondly,two Lab VIEW acquisition programs,rapid-scan and step-scan method are introduced.Finally,the rotationally-resolved spectrum of the C-O stretching fundamental band of hydroxyacetone in the region of 1285.0-1290.5cm-1 is recorded by this experimental setup.In addition,the assignment and analysis of the observed spectrum is carried out by using the PGOPHER program.A total of 100 transitions arising from A-species have been assigned and the standard deviation of the least-square fit is about 0.0027 cm-1.Nine molecular parameters in the excited vibrational state are determined and the band-origin is around 1290.3452 cm-1.