Knowledge Bank

Very high resolution (0 .0005 $cm-1$) infrared spectra of $NO2$ have been recorded with a pulse driven diode laser spectrometer.The $1600cm-1$ region correspoding to the $\nu 3$-band has been analysed. 34 lines ($6\le N\prime \prime \le 38,0\le Ko0\le 11$) with $NO2$ pressure varying from 0.1 to 0.5 Torr and foreign gas (Xe, Kr, Ar,...) from 100 to 220 Torr were recorded using a Herriot cell of 4.7m pathlength due the weakness of lines. The results, clearly shows (within experimental accuracy) a notable variation of shift with respect to $N\prime \prime$ quantum number, the shifts being larger in negativ magnitude for big $N\prime \prime$. One can also note that the values of shifts are not systematically lower for molecules with higher broadening coefficients as it is for $H2O$. The similarities and differences between $H2O$ and $NO2$ will be discussed.