The high detection sensitivity available from intracavity laser spectroscopy (ILS) is extended into the near infrared by solid-state laser systems operating with relatively narrow (~0.002 [micro]m) bandwidths for three [CO.sub.2] absorption features of importance to an understanding of planetary atmospheres. The absolute intensities and pressure-broadening properties of the P(12), P(14), and P(16) lines of the [Sigma]-[Sigma] band (12 [degrees] 1-00 [degrees] 0) of [CO.sub.2] (at 2.0129, 2.0136, and 2.0143 [micro]m) are measured quantitatively by ILS with a Tm:YAG laser operating near 2.0 [micro]m. The temperature dependencies of these absolute intensities and collisional-broadening parameters for these three [CO.sub.2] features are also measured over the 110-300 K range. The 3.0-km equivalent absorption path length available from the ILS Tm:YAG system is used to enhance detection sensitivity by more than a factor of 1.5 x [10.sup.4] while maintaining a physical sample cell path length of ~20 cm. The enhanced detection sensitivity of ILS permits absolute intensities and collisional-broadening parameters to be measured from [is less than] 1-Torr [CO.sub.2] over a series of temperatures, conditions that emulate those found in the atmospheres of Mars, Triton, and Venus. [C] 2001 Optical Society of America OCIS codes: 120.1880, 120.4820, 140.3070, 140.3480, 300.6390, 350.1270.