Multiphoton ionization of N(2) by the third harmonic of a Nd:YAG laser: a new avenue for air diagnostics.
Ionization of N(2) by the third harmonic of a Nd:YAG laser is demonstrated and confirmed experimentally from both spectral and ion-collection measurements. Six photons at 355 nm excite the ground-state neutral molecule to the B(2) summation operator(+)(u) (upsilon' = 8) ionized state. Intense radiation at 391.4 nm associated with the B(2) summation operator(+)(u) (upsilon = 0) ? X(2) summation operator(+)(g) (upsilon'' = 0) transition was detected. The intensity of this line scales quadratically with the laser power. An ion concentration of 3.25 x 10(13) ions/cm(3) was detected after irradiation by a 45-mJ laser pulse focused to a diameter of 17 microm. The potential application of this ionization scheme for air velocity and temperature measurements is presented.
Laufer
G
G
Krauss
R H
RH
Grinstead
J H
JH