Collisions near threshold in atomic and molecular physics

Sadeghpour, H. R.; Bohn, John L.; Cavagnero, M. J.; Esry, B. D.; Fabrikant, I. I.; Macek, J. H.; Rau, A. R. P.

doi:10.1088/0953-4075/33/5/201

Cited by 243 publications

(209 citation statements)

References 165 publications

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“…In Fig. 1 (a), we see that the fermionic cross section (σ f ) is Wigner suppressed, as expected [15]. This is in contrast to 3D where all non-zero partial wave become energy independent as energy goes to zero [10].…”

supporting

confidence: 56%

Two-dimensional dipolar scattering

Ticknor

2009

Phys. Rev. A

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We characterize the long range dipolar scattering in 2-dimensions. We use the analytic zero energy wavefunction including the dipolar interaction; this solution yields universal dipolar scattering properties in the threshold regime. We also study the semi-classical dipolar scattering and find universal dipolar scattering for this energy regime. For both energy regimes, we discuss the validity of the universality and give physical examples of the scattering. [3]. Such theories show dipolar systems will lead to exotic and highly correlated quantum systems. Reduced dimensionality also offers another level of control to exert over ultracold matter. In pursuit of such quantum systems, there has been exciting experimental progress in the production of polar molecules [4,5] and in the production of quasi-2 dimensional ultracold gases [6,7]. This makes it seem that the experimental production of 2D dipolar gases is at hand. However, there is no simple understanding of dipolar scattering in 2D, even for the case of the long range scattering. Such an understanding is an important first step in the study of these quantum systems. In this paper we study the properties of long range dipolar scattering in 2D and present estimates of the scattering cross section. We consider the scenario when the polarization of the molecules (d =ẑ) is perpendicular to the plane of motion (ρ = x 2 + y 2 , d ·ρ = 0). We do not consider the complications of transverse confinement. Under these simplifications the dipolar interaction is: V dd = d 2 /ρ 3 , where d is the magnitude of the induced dipole moment. The anisotropy of the interaction has been removed and the interaction is purely repulsive.To understand the scattering we use the dipolar length scale: D = µd 2 / 2 where µ is the reduced mass. In polar molecules this length scale can be quite large, orders of magnitude larger than the range of the short range interaction, ρ 0 . Using D to rescale the 2D radial Schrödinger equation and expanding in partial waves, ψ(ρ, ϕ) = m e imϕ φ m (ρ)/ √ρ , the result is:whereρ = ρ/D, k 2 = 2µE/ 2 , and E is the scattering energy. Ifρ = ρ 0 /D ≪ 1 then the only degree of freedom is Dk, so once Eq. (1) is solved for a given Dk the resulting scattering will apply to any quantum mechanical 2D dipolar system; this is universal dipolar scattering [8, 9, 10].We have analyzed Eq. (1) and characterized the long range 2D dipolar scattering. We present analytic estimates of the scattering in both the threshold and semiclassical limits. In contrast to 3D, there is a diagonal s-wave dipolar interaction, and this leads to universal dipolar scattering in the threshold regime. We refer to the isotropic m = 0 partial wave as s-wave. For threshold scattering in 3D, it is required that a s ≪ D to have universal dipolar scattering [9,10]. This is challenging because a s , the s-wave scattering length, depends sensitively on the details of the short range interaction. However in 2D, the repulsive dipolar interaction prevents ultracold particles from reaching the short rang...

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supporting

confidence: 56%

Two-dimensional dipolar scattering

Ticknor

2009

Phys. Rev. A

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“…In zero field, the molecules are completely unpolarized, and the dipoledipole interaction vanishes. Thus the cross sections obey the familiar Wigner threshold laws for short-ranged interactions between fermions: the elastic cross section σ el ∝ E 2 , whereas the (exothermic) inelastic cross section σ inel ∝ E 1/2 [40]. Thus in zero field elastic scattering is actually less likely than inelastic scattering at lower energies (below about 10µK in this example).…”

Section: Collision Cross Sections For Odmentioning

confidence: 67%

“…Threshold laws for various power-law long-range potentials have been written about extensively in the past [28,29,30,31,32,33,34,35,36,37,38,39,40,41]. In this section we summarize the main results relevant to the energy dependence of cross sections, using the first Born approximation to make the math transparent.…”

Section: Threshold Laws In the Born Approximationmentioning

confidence: 99%

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Ultracold collisions of fermionic OD radicals

Авдеенков

Bohn

2005

Phys. Rev. A

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We discuss consequences of Fermi exchange symmetry on collisions of polar molecules at low temperatures (below 1 K), considering the OD radical as a prototype. At low fields and low temperatures, Fermi statistics can stabilize a gas of OD molecules against state-changing collisions. We find, however, that this stability does not extend to temperatures high enough to assist with evaporative cooling. In addition, we establish that a novel "field-linked" resonance state of OD dimers exists, in analogy with the similar states predicted for bosonic OH.

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“…Some aspects of resonance and threshold phenomena were discussed in these reviews, as well as by Sadeghpour et al (2000). The theoretical description of electron-molecule collisions generally requires an adequate description of electronic, vibrational and rotational degrees of freedom.…”

Section: Theorymentioning

confidence: 99%