INFRARED DIODE LASER SPECTROSCOPY OF JET-COOLED Ni(CO)$_3$($^{13}$CO) AND NiCO

Abstract

The two major isotopic species ($^{58}$Ni and $^{60}$Ni) of Ni(CO)$_3$($^{13}$CO) and NiCO have been investigated with a recently constructed infrared spectrometer. These molecules were observed by implementing a slit jet pulsed nozzle coupled to a modulated electrical discharge and a lock-in detection system. Typical nozzle pulses were approximately 2ms in duration, during which time the electrical discharge was modulated at a frequency of 15 kHz. Modulation of the electrical discharge allowed the use of a lock-in detector to improve the signal to noise ratio. A lead salt diode laser beam was multipassed across the output of the slit jet for 15 passes using a Perry cell, and the transmitted IR intensity was monitored. Analysis of the resulting spectra for the $^{13}$CO and CO stretching modes in Ni(CO)$_3$($^{13}$CO) and NiCO respectively, lead to the following constants (1$\sigma$ errors limits in parentheses): \begin{center} \begin{tabular}{ccccc} \hline & $^{58}$Ni(CO)$_3$($^{13}$CO) & $^{60}$Ni(CO)$_3$($^{13}$CO) & $^{58}$NiCO & $^{60}$NiCO \ \hline \hline $\nu_0$ (cm$^{-1}$) & 2022.075753(95) & 2021.936884(181) & 2010.692843(605) & 2010.645425(529) \ B$^{\prime\prime }$ (cm$^{-1}$) & 0.034736(2) & 0.033763(4) & 0.151094(8) & 0.149598(7) \ B$^{\prime }$ (cm$^{-1}$) & 0.034688(2) & 0.033709(3) & 0.150244(9) & 0.148741(5) \ \hline \end{tabular} \end{center}