IntermolecularV-Venergy transfer in the photodissociation of weakly bound complexes: A new experimental approach

Intermolecular V–V energy transfer in the photodissociation of CO2–HF(v=1)

“…The apparatus used in the present experiments has been discussed in detail elsewhere, 16,17,30,37 so that only a brief overview is required here. The two F-center laser systems used in the present study are each equipped with an evacuated chamber, which houses confocal etalons with free spectral ranges of 150, 750 MHz, and 7.5 GHz.…”

Spectroscopy and energetics of the acetylene molecule: dynamical complexity alongside structural simplicity

“…Á % 0.007 cm À1 FWHM for the 3313.56-cm À1 R(0) transition of HCN-He N [46,291]). Linewidths for CH 4 in He droplets range from 0.2 cm À1 to 1.1 cm À1 [290], depending on the rotational and vibrational relaxation channels that are available to states with different nuclear-spin symmetries (A, E, F). Likewise, measured linewidths Á for 12 C 2 H 2 , 12 C 13 CH 2 , 13 C 2 H 2 , and 12 C 2 HD in He droplets vary within the range 0.01-0.3 cm À1 and can be rationalized in terms of available rotational and vibrational relaxation channels, nuclear-spin symmetry constraints, and droplet-size effects [44].…”

“…Acetylene has played a key role in studies by Miller [4] to investigate intermolecular V-V transfer in N 2 -HF and CO 2 -HF) uses two narrowband cw near-IR SLM-tunable F-centre lasers, each with a set of multipass mirrors: the complex is photodissociated by the first (PUMP) laser and the internal rovibrationalstate distributions of the monomer fragments are then detected optothermally at an adjustable scattering angle by the second (PROBE) laser. Such molecular-beam PHOFAD (photodissociation angular distribution) experiments provide insight into channels of energy disposal into the photofragments.…”

“…where V i designates vibrational quanta in each of the normal modes (i ¼ [1][2][3][4][5] and ' is the resultant vibrational angular momentum quantum number, ' ¼ ' 4 þ ' 5 (alternatively designated as k in some of the literature). Moreover, values of ' 4 and ' 5 also need to be explicitly specified whenever V 4 and V 5 are non-zero.…”

“…Roger also spent a month or so in Sydney with my research group in 1992, by which time I had moved to Macquarie University; this resulted eventually in our only joint paper, on optical double-resonance spectroscopy of the acetylene-argon van der Waals complex [3]. During his time in Sydney, Roger and I had adjacent offices which facilitated frequent enthusiastic discussions of his evolving ideas on intermolecular vibrational energy transfer in photodissociation of van der Waals and H-bonded complexes [4], his emerging interest in observing pendular states to orient such complexes [5] and determine their photofragment distributions [6][7][8], and his plans for further initiatives in spectroscopy of aerosols in low-temperature diffusion cells [9][10][11][12][13]. Our subsequent encounters were occasional and all too few, alas!…”