A New Type High Quality Spherical Photoacoustic Cell for Laser Photoacoustic Spectroscopy

At first we carried out the theoretical study of the acoustic characters of a spherical photoacoustic cell,the calculation shows that the spherical cell has a high Q quantity over the commonly used cylinder shape cell.Then we constructed a high resolution laser photoacoustic spectrometer with a spherical shape photoacoustic cell and Ti:sapphire laser and measured the acoustic modes in the spherical shape cell,the experimental results is in accordance with the theoretical results.The Q quantity of the first radial mode of the spherical cell attains 590,which is much better than that of the cylinder shape cell in ref..With this spectrometer measured the weak spectrum of acetylene near 12750cm^-1,the comparison with the result of the Intra-Cavity Laser Absorption Spectrometer（ICLAS）in our laboratory shows that get better resolution and better signal to noise ratio（SNR）,the detection sensitivity of this spectrometer is estimated to be 6×10^-8cm^-1（1:1 SNR）.