Biomedical subjects

Patrick Medley

Publications and source records attributed to Patrick Medley.

3 recordsLinked to original sources

PubMed2006

Imaging the Mott insulator shells by using atomic clock shifts.

Microwave spectroscopy was used to probe the superfluid-Mott insulator transition of a Bose-Einstein condensate in a three-dimensional optical lattice. By using density-dependent transition frequency shifts, we were able to spectroscopically distinguish sites with different occupation numbers and to directly image sites with occupation numbers from one to five, revealing the shell structure of the Mott insulator phase. We used this spectroscopy to determine the onsite interaction and lifetime for individual shells.

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PubMed2006

Rovibrational spectra of the N2-HF complex at the vHF=3 level.

We report the analyses of the three intermolecular combination bands of the hydrogen-bonded N2-HF complex at vHF=3, observed by molecular beam intracavity laser induced fluorescence. The origin of the HF intermolecular bending combination band, (3001(1)0)<--(00000), is 11 548.45(3) cm(-1), 328.2 cm(-1) higher than that of the (30000)<--(00000) transition with an origin at 11 220.250(1) cm(-1). The average rotational constant of the (3001(1)0) level is 0.103 63(1) cm(-1), a 4.8% reduction from B(30000)=0.109 21(1) cm(-1). Perturbations are observed as line splittings, increased line widths, and reduced peak intensities of a number of lines of the e and f components of (3001(1)0). In addition, the centrifugal distortion coefficients of both components are large, negative, and different. The N2 intermolecular bend transition (30001(1))<--(00000) has an origin at 11 288.706(1) cm(-1), 68.456(2) cm(-1) above that of the (30000)<--(00000) transition. This is the lowest combination state at v(HF)=3 level. It is unperturbed, yielding B(30001(1))=0.110.10(1) cm(-1). The transition to the intermolecular stretching state, (30100)<--(00000), has an origin at 11 318.858(1) cm(-1) with B(30100)=0.105 84(1) cm(-1). Both the (30100) and (30000) levels show an isolated perturbation at J=4. The Lorentzian component of the line widths, which show considerable variation with soft mode, are GammaL(30000)=490(30) MHz, GammaL(30100)=630(30) MHz, GammaL(3001(1)0)=250(30) MHz, and GammaL(30001(1))=500(50) MHz.

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PubMed2004

Spectroscopy of the OC-HF hydrogen-bonded complex at vHF=3.

The v(HF)=3 levels of the linear OC-HF complex are observed in the range of 10,800-11,500 cm(-1) using intracavity Ti-sapphire laser-induced fluorescence. The vibrational predissociation linewidths of both (30000) and (3001(1)0) states exceed 5 GHz; thus, the measured spectra are not rotationally resolvable. Under the assumption that these levels are not strongly perturbed, the rotational constants of the two levels are determined to be 0.1100(1) cm(-1) for (30000), 0.1081(1), and 0.1065(1) cm(-1) for f and e sublevels of (3001(1)0), respectively, through band contour fitting. The (30000)<--(00000) band origin is at 10,894.46(1) cm(-1), showing a HF wave number redshift of 478.3 cm(-1). The 4.07 redshift ratio of v(HF)=3 to that of v(HF)=1 indicates a significantly nonlinear increase of the intermolecular interaction energy through HF valence excitation. An ab initio interaction potential surface for HF valence coordinates varying from 0.8 to 1.25 A is used to examine vibrational dynamics. The HF valence vibration v(1) is treated perturbatively, showing that the vibrational redshifts are determined essentially in first order with only a very small second-order contribution. The (3001(1)0)<--(00000) combination transition is observed with the band origin at 11,432.66(1) cm(-1), giving the HF intermolecular bending mode to be 538.2 cm(-1). The high frequency of this vibration, compared to that in similar HF complexes, shows the strong angular anisotropy of the intermolecular interaction potential of OC-HF with respect to the HF subunit. The lifetime of the (3001(1)0) level increases to 28 ps from 14 ps for (30000).

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