Resonant microwave coherence transfer between two levels pairs ( $a-a^{\\prime}$ ) and ( $b-b^{\\prime}$ ) of two molecular species A and B has been observed. A and B are either different molecules or the same molecule in states uncoupled by collision induced transitions. The frequencies of the two transitions $a \\rightarrow a^{\\prime}$ and $b \\rightarrow b^{\\prime}$ are nearly equal and can be transiently brought in coincidence by applying a suitable Stark field. The coherence transferred from A-molecules to the B-molecules is detected by the techniques of time resolved spectroscopy. The observed phenomena may be interpreted either by collision induced effects between collision partner molecules or by collective effects. The contribution of these two effects are roughly estimated.Resonant microwave coherence transfer between two levels pairs ($a-a^{\\prime}$) and ($b-b^{\\prime}$) of two molecular species A and B has been observed. A and B are either different molecules or the same molecule in states uncoupled by collision induced transitions. The frequencies of the two transitions $a \\rightarrow a^{\\prime}$ and $b \\rightarrow b^{\\prime}$ are nearly equal and can be transiently brought in coincidence by applying a suitable Stark field. The coherence transferred from A-molecules to the B-molecules is detected by the techniques of time resolved spectroscopy. The observed phenomena may be interpreted either by collision induced effects between collision partner molecules or by collective effects. The contribution of these two effects are roughly estimated.

Jan 1, 19770 citations

Resonant Rydberg–Rydberg collisions

Thomas F. Gallagher

Resonant energy transfer collisions, those in which one atom or molecule transfers only internal energy, as oppposed to translational energy, to its collision partner require a precise match of the energy intervals in the two collision partners. Because of this energy specificity, resonant collisional energy transfer plays an important role in many laser applications, the He–Ne and CO 2 lasers being perhaps the best known examples. It is interesting to imagine an experiment in which we can tune the energy of the excited state of atom B through the energy of the excited state of atom A, as shown in Fig. 14.1. At resonance we would expect the cross section for collisionally transferring the energy from an excited A atom to a ground state B atom to increase sharply as shown in Fig. 14.1. In general, atomic and molecular energy levels are fixed, and the situation of Fig. 14.1 is impossible to realize. Nonetheless systematic studies of resonant energy transfer have been carried out by altering the collision partner, showing the importance of resonance in collisional energy transfer. The use of atomic Rydberg states, which have series of closely spaced levels, presents a natural opportunity for the study of resonant collisional energy transfer. One of the earliest experiments was the observation of resonant rotational to electronic energy transfer from NH 3 to Xe Rydberg atoms by Smith et al .Resonant energy transfer collisions, those in which one atom or molecule transfers only internal energy, as oppposed to translational energy, to its collision partner require a precise match of the energy intervals in the two collision partners. Because of this energy specificity, resonant collisional energy transfer plays an important role in many laser applications, the He–Ne and CO 2 lasers being perhaps the best known examples. It is interesting to imagine an experiment in which we can tune the energy of the excited state of atom B through the energy of the excited state of atom A, as shown in Fig. 14.1. At resonance we would expect the cross section for collisionally transferring the energy from an excited A atom to a ground state B atom to increase sharply as shown in Fig. 14.1. In general, atomic and molecular energy levels are fixed, and the situation of Fig. 14.1 is impossible to realize. Nonetheless systematic studies of resonant energy transfer have been carried out by altering the collision partner, showing the importance of resonance in collisional energy transfer. The use of atomic Rydberg states, which have series of closely spaced levels, presents a natural opportunity for the study of resonant collisional energy transfer. One of the earliest experiments was the observation of resonant rotational to electronic energy transfer from NH 3 to Xe Rydberg atoms by Smith et al .

Cambridge University Press eBooksSep 15, 19940 citations

Collision-Induced Coherences in Optical Physics

G. S. Agarwal

Advances in atomic, molecular, and optical physicsJan 1, 199110 citations

Hyperfine structure transfer, fine structure transfer, and quenching of 113Cd atoms in the 5s5p 3P1 state by collisions with molecular gases

Th. von der Haar, C. Kramer, M. Baumann

Collisions of excited 113Cd(5 3P1) atoms with various molecular gases (N2, H2, D2, CO, CO2, CH4, C2H6, C2H4, O2) have been investigated using atomic fluorescence spectroscopy. By selective excitation of a hyperfine structure level with a pulsed dye laser and studying the time dependence of the fluorescence signals as a function of the buffer gas density the cross sections for quenching, fine structure transfer, and hyperfine structure transfer could be obtained. For N2 molecules the collisions can be described by a decoupling model as has been shown previously for the noble gases as collision partners.Collisions of excited 113Cd(5 3P1) atoms with various molecular gases (N2, H2, D2, CO, CO2, CH4, C2H6, C2H4, O2) have been investigated using atomic fluorescence spectroscopy. By selective excitation of a hyperfine structure level with a pulsed dye laser and studying the time dependence of the fluorescence signals as a function of the buffer gas density the cross sections for quenching, fine structure transfer, and hyperfine structure transfer could be obtained. For N2 molecules the collisions can be described by a decoupling model as has been shown previously for the noble gases as collision partners.

The Journal of Chemical PhysicsFeb 1, 19917 citations

Resonant microwave coherence transfer between two levels pairs (

a-a^{\\prime}

) and (

b-b^{\\prime}

) of two molecular species A and B has been observed. A and B are either different molecules or the same molecule in states uncoupled by collision induced transitions. The frequencies of the two transitions

a \\rightarrow a^{\\prime}

and

b \\rightarrow b^{\\prime}

are nearly equal and can be transiently brought in coincidence by applying a suitable Stark field. The coherence transferred from A-molecules to the B-molecules is detected by the techniques of time resolved spectroscopy. The observed phenomena may be interpreted either by collision induced effects between collision partner molecules or by collective effects. The contribution of these two effects are roughly estimated.