Multiphoton induced fluorescence and ionization of carbon monoxide (B 1Σ+)

Abstract

The B 1Σ+ state of carbon monoxide was created by a two-photon absorption of 230 nm laser radiation. The B 1Σ+ state was identified by the positions of the Q branch 0–0 absorption band and the vibrational bands of B 1Σ+ → A 1Π fluorescence occurring after excitation. Collision-induced b 3Σ+ → a 3Π emission in the 350 nm region was also observed. The lifetimes of the B 1Σ+ → A 1Π and the b 3Σ+ → a 3Π emission were obtained as well as the self-quenching rate constants and the CO (B 1Σ)) quenching rate by N2. In addition to the two-photon laser induced fluorescence of B 1Σ+ carbon monoxide, a three-photon resonant (2+1) ionization was observed. Laser power dependence studies indicate that ionization of the B 1Σ+ state was nearly saturated at the laser fluence used, implying that most CO (B 1Σ+) was ionized rather than fluorescing. The measured polarization ratios for circularly to linearly polarized excitation of fluorescence and ionization was much larger than the expected values suggesting that other three-photon processes are occurring and occur more efficiently for linear polarization.

State to state He–CO rotationally inelastic scattering

“…40,41 The second harmonic of an injection seeded Nd:YAG laser ͑Spectra-Physics/Larry Wolford Services͒ pumped a Continuum dye laser, and the dye laser output was doubled in a KDP crystal. The doubled output was then mixed with the YAG fundamental in KDP for probing through the B state near 230 nm, or with the dye laser fundamental in BBO for probing through the E state near 215 nm.…”

A velocity map ion-imaging study on ketene photodissociation at 208 and 213nm: Rotational dependence of product angular anisotropy

“…Lines starting in rotational levels up to JЉ =76 in Љ = 0 and up to JЉ =47 in Љ = 1 can be assigned. CO͑B 1 ⌺ + , =0͒ state is weakly predissociative for J ജ 38, 27 Rottke and Zacharias 28 have reported that the rate of predissociation is J independent. The line intensity decrease in =1, J = 18, and J = 36 are also observed, which are due to the CO͑B 1 ⌺ + ͒ state predissociated by other states.…”

Internuclear-axis angular distribution in multiphoton excitation

“…Thus it is convenient to write the angular distribution in terms of the From Eqs. (21), (22), and (25) we see that the excitation probability is nonvanishing only when Q"=q, +q2+ . +q"=Of -0 =b,Q.…”

“…In fact, we may see from Eq. (25) that the tensor component elk'. is the n-photon rotational line factor similar to the one-photon case [19,11,18].…”