Ryan Carollo | University of Connecticut (original) (raw)

Papers by Ryan Carollo

Research paper thumbnail of Two-Photon Vibrational Transitions in 16O2+ as Probes of Variation of the Proton-to-Electron Mass Ratio

Atoms

Vibrational overtones in deeply-bound molecules are sensitive probes for variation of the proton-... more Vibrational overtones in deeply-bound molecules are sensitive probes for variation of the proton-to-electron mass ratio μ . In nonpolar molecules, these overtones may be driven as two-photon transitions. Here, we present procedures for experiments with 16 O 2 + , including state-preparation through photoionization, a two-photon probe, and detection. We calculate transition dipole moments between all X 2 Π g vibrational levels and those of the A 2 Π u excited electronic state. Using these dipole moments, we calculate two-photon transition rates and AC-Stark-shift systematics for the overtones. We estimate other systematic effects and statistical precision. Two-photon vibrational transitions in 16 O 2 + provide multiple routes to improved searches for μ variation.

Research paper thumbnail of Resonant Coupling of the 2(1), 4(1) and Spectroscopy of the 3^3Π Excited States of Ultracold KRb Molecules

Frontiers in Optics 2012/Laser Science XXVIII, 2012

Research paper thumbnail of Spectroscopy of^ 39K^ 85Rb electronic states in the predicted region of resonantly coupled excited states for the direct formation of the X (0, 0) state

ABSTRACT The 2^1π(v'=17) and 1^1π(v'=60) vibrational levels of KRb are predicted ... more ABSTRACT The 2^1π(v'=17) and 1^1π(v'=60) vibrational levels of KRb are predicted to be resonantly coupled, based on extrapolation from high rotational levels reported in [1] to J' =1 [2], and on tentative assignments of photoassociation spectra in the region near 12535cm-1 [3]. Access to the 2^1π levels is desirable for formation of ultracold KRb molecules in their ground X^1σ^+, v=0, J=0 level because of strong Franck-Condon overlap [3]. The 1^1π component of these two mixed states provides PA access to short range region where 2^1π emission to the X(0,0) level can occur. Experiments are being carried out to better understand the spectra and perturbations in the region near 12535cm-1, which should include 3(0^+), 2(1), 4(1), 5(1) and possibly other states. The 4(1) and 5(1) long-range states correlate with 1^1π and 2^1π short-range states. These studies have also produced new information on efficient formation of specific vibrational levels in a^3σ^+ state and new data on 3^3σ^+ and 3^3π states. [4pt] [1] Kasahara et al., JCP 111, 19 (1999)[0pt] [2] Wang et al, EPJD 31, 165 (2004)[0pt] [3] Stwalley et al., JPCA 114, 81 (2010)

Research paper thumbnail of Resonant Coupling in the Heteronulcear Alkali Dimers for Direct Photoassociative Formation of X ^1&+circ; v''= 0 Ultracold Molecules

We have studied the resonant coupling between rovibronic levels of different electronic states fo... more We have studied the resonant coupling between rovibronic levels of different electronic states for the ten heteronuclear alkali dimers formed from combinations of Li, Na, K, Rb, and Cs. We focus on the energy range < 100 cm-1 below the lowest two excited asymptotes, which is relevant for photoassociative molecule formation. Within this range, we concentrate on coupled levels that

Research paper thumbnail of Excitation of Weakly Bound Molecules to Trilobitelike Rydberg States

Physical Review Letters, 2013

We observe "trilobite-like" states of ultracold 85 Rb2 molecules, in which a ground-state atom is... more We observe "trilobite-like" states of ultracold 85 Rb2 molecules, in which a ground-state atom is bound by the electronic wavefunction of its Rydberg-atom partner. We populate these states through the ultraviolet excitation of weakly-bound molecules, and access a regime of trilobite-like states at low principal quantum numbers and with vibrational turning points around 35 Bohr radii. This demonstrates that, unlike previous studies that used free-to-bound transitions, trilobite-like states can also be excited through bound-to-bound transitions. This approach provides high excitation probabilities without requiring high-density samples, and affords the ability to control the excitation radius by selection of the initial-state vibrational level.

Research paper thumbnail of Direct photoassociative formation of ultracold KRb molecules in the lowest vibrational levels of the electronic ground state

Physical Review A, 2012

We report continuous direct photoassociative formation of ultracold KRb molecules in the lowest v... more We report continuous direct photoassociative formation of ultracold KRb molecules in the lowest vibrational levels (v ′′ = 0 − 10) of the electronic ground state (X 1 Σ + ), starting from 39 K and 85 Rb atoms in a magneto-optical trap. The process exploits a newfound resonant coupling between the 2(1), v ′ = 165 and 4(1), v ′ = 61 levels, which exhibit an almost equal admixture of the uncoupled eigenstates. The production rate of the X 1 Σ + (v ′′ =0) level is estimated to be 5 × 10 3 molecules/sec.

Research paper thumbnail of Shortcuts for understanding rovibronic spectroscopy of ultracold alkali metal diatomic molecules

Molecular Physics, 2012

The high-resolution rovibronic spectroscopies of cold and ultracold molecules (e.g. supersonic mo... more The high-resolution rovibronic spectroscopies of cold and ultracold molecules (e.g. supersonic molecular beam excitation spectra (MB), photoassociation spectra of ultracold atoms (PA), resonance-enhanced multiphoton ionization spectra (REMPI), stimulated Raman transfer (SRT) spectra) are of major current interest. This manuscript summarizes the significant level of understanding of these various spectroscopies, enabled by using simple graphical and semiclassical ideas and shortcuts. Physical

Research paper thumbnail of Spectroscopy and applications of the 3 3Σ+ electronic state of 39K85Rb

The Journal of Chemical Physics, 2013

We report new results on the spectroscopy of the 3 (3)Σ(+) electronic state of (39)K(85)Rb. The o... more We report new results on the spectroscopy of the 3 (3)Σ(+) electronic state of (39)K(85)Rb. The observations are based on resonance-enhanced multiphoton ionization of ultracold KRb molecules starting in vibrational levels v'' = 18-23 of the a (3)Σ(+) state and ionized via the intermediate 3 (3)Σ(+) state. The a-state ultracold molecules are formed by photoassociation of ultracold (39)K and (85)Rb atoms to the 3(0(+)) state of KRb followed by spontaneous emission. We discuss the potential applications of this state to future experiments, as a pathway for populating the lowest vibrational levels of the a state as well as the X state.

Research paper thumbnail of Spectroscopy of the double minimum 3 3ΠΩ electronic state of 39K85Rb

The Journal of Chemical Physics, 2013

We report the observation and analysis of the 3 (3)ΠΩ double-minimum electronic excited state of ... more We report the observation and analysis of the 3 (3)ΠΩ double-minimum electronic excited state of (39)K(85)Rb. The spin-orbit components (0(+), 0(-), 1, and 2) of this state are investigated based on potentials developed from the available ab initio potential curves. We have assigned the vibrational levels v' = 2-11 of the 3 (3)Π1,2 potentials and v' = 2-12 of the 3(3)Π0(+/-) potential. We compare our experimental observations of the 3 (3)ΠΩ state with predictions based on theoretical potentials. The observations are based on resonance enhanced multiphoton ionization of ultracold KRb in vibrational levels v" = 14-25 of the a (3)Σ(+) state. These a-state ultracold molecules are formed by photoassociation of ultracold (39)K and (85)Rb atoms to the 5(1) state of KRb followed by spontaneous emission to the a state.

Research paper thumbnail of Resonant Coupling in the Heteronuclear Alkali Dimers for Direct Photoassociative Formation of X(0,0) Ultracold Molecules

The Journal of Physical Chemistry A, 2010

Promising pathways for photoassociative formation of ultracold heteronuclear alkali metal dimers ... more Promising pathways for photoassociative formation of ultracold heteronuclear alkali metal dimers in their lowest rovibronic levels (denoted X(0,0)) are examined using high quality ab initio calculations of potential energy curves currently available. A promising pathway for KRb, involving the resonant coupling of the 2 1 Π and 1 1 Π states just below the lowest excited asymptote (K(4s)+Rb(5p 1/2 )), is found to occur also for RbCs and less promisingly for KCs as well. The resonant coupling of the 3 1 Σ + and 1 1 Π states, also just below the lowest excited asymptote, is found to be promising for LiNa, LiK, LiRb, and less promising for LiCs and KCs. Direct photoassociation to the 1 1 Π state near dissociation appears promising in the final dimers, NaK, NaRb, and NaCs, although detuning more than 100 cm −1 below the lowest excited asymptote may be required.

Research paper thumbnail of Two-Photon Vibrational Transitions in 16O2+ as Probes of Variation of the Proton-to-Electron Mass Ratio

Atoms

Vibrational overtones in deeply-bound molecules are sensitive probes for variation of the proton-... more Vibrational overtones in deeply-bound molecules are sensitive probes for variation of the proton-to-electron mass ratio μ . In nonpolar molecules, these overtones may be driven as two-photon transitions. Here, we present procedures for experiments with 16 O 2 + , including state-preparation through photoionization, a two-photon probe, and detection. We calculate transition dipole moments between all X 2 Π g vibrational levels and those of the A 2 Π u excited electronic state. Using these dipole moments, we calculate two-photon transition rates and AC-Stark-shift systematics for the overtones. We estimate other systematic effects and statistical precision. Two-photon vibrational transitions in 16 O 2 + provide multiple routes to improved searches for μ variation.

Research paper thumbnail of Resonant Coupling of the 2(1), 4(1) and Spectroscopy of the 3^3Π Excited States of Ultracold KRb Molecules

Frontiers in Optics 2012/Laser Science XXVIII, 2012

Research paper thumbnail of Spectroscopy of^ 39K^ 85Rb electronic states in the predicted region of resonantly coupled excited states for the direct formation of the X (0, 0) state

ABSTRACT The 2^1π(v'=17) and 1^1π(v'=60) vibrational levels of KRb are predicted ... more ABSTRACT The 2^1π(v'=17) and 1^1π(v'=60) vibrational levels of KRb are predicted to be resonantly coupled, based on extrapolation from high rotational levels reported in [1] to J' =1 [2], and on tentative assignments of photoassociation spectra in the region near 12535cm-1 [3]. Access to the 2^1π levels is desirable for formation of ultracold KRb molecules in their ground X^1σ^+, v=0, J=0 level because of strong Franck-Condon overlap [3]. The 1^1π component of these two mixed states provides PA access to short range region where 2^1π emission to the X(0,0) level can occur. Experiments are being carried out to better understand the spectra and perturbations in the region near 12535cm-1, which should include 3(0^+), 2(1), 4(1), 5(1) and possibly other states. The 4(1) and 5(1) long-range states correlate with 1^1π and 2^1π short-range states. These studies have also produced new information on efficient formation of specific vibrational levels in a^3σ^+ state and new data on 3^3σ^+ and 3^3π states. [4pt] [1] Kasahara et al., JCP 111, 19 (1999)[0pt] [2] Wang et al, EPJD 31, 165 (2004)[0pt] [3] Stwalley et al., JPCA 114, 81 (2010)

Research paper thumbnail of Resonant Coupling in the Heteronulcear Alkali Dimers for Direct Photoassociative Formation of X ^1&+circ; v''= 0 Ultracold Molecules

We have studied the resonant coupling between rovibronic levels of different electronic states fo... more We have studied the resonant coupling between rovibronic levels of different electronic states for the ten heteronuclear alkali dimers formed from combinations of Li, Na, K, Rb, and Cs. We focus on the energy range < 100 cm-1 below the lowest two excited asymptotes, which is relevant for photoassociative molecule formation. Within this range, we concentrate on coupled levels that

Research paper thumbnail of Excitation of Weakly Bound Molecules to Trilobitelike Rydberg States

Physical Review Letters, 2013

We observe "trilobite-like" states of ultracold 85 Rb2 molecules, in which a ground-state atom is... more We observe "trilobite-like" states of ultracold 85 Rb2 molecules, in which a ground-state atom is bound by the electronic wavefunction of its Rydberg-atom partner. We populate these states through the ultraviolet excitation of weakly-bound molecules, and access a regime of trilobite-like states at low principal quantum numbers and with vibrational turning points around 35 Bohr radii. This demonstrates that, unlike previous studies that used free-to-bound transitions, trilobite-like states can also be excited through bound-to-bound transitions. This approach provides high excitation probabilities without requiring high-density samples, and affords the ability to control the excitation radius by selection of the initial-state vibrational level.

Research paper thumbnail of Direct photoassociative formation of ultracold KRb molecules in the lowest vibrational levels of the electronic ground state

Physical Review A, 2012

We report continuous direct photoassociative formation of ultracold KRb molecules in the lowest v... more We report continuous direct photoassociative formation of ultracold KRb molecules in the lowest vibrational levels (v ′′ = 0 − 10) of the electronic ground state (X 1 Σ + ), starting from 39 K and 85 Rb atoms in a magneto-optical trap. The process exploits a newfound resonant coupling between the 2(1), v ′ = 165 and 4(1), v ′ = 61 levels, which exhibit an almost equal admixture of the uncoupled eigenstates. The production rate of the X 1 Σ + (v ′′ =0) level is estimated to be 5 × 10 3 molecules/sec.

Research paper thumbnail of Shortcuts for understanding rovibronic spectroscopy of ultracold alkali metal diatomic molecules

Molecular Physics, 2012

The high-resolution rovibronic spectroscopies of cold and ultracold molecules (e.g. supersonic mo... more The high-resolution rovibronic spectroscopies of cold and ultracold molecules (e.g. supersonic molecular beam excitation spectra (MB), photoassociation spectra of ultracold atoms (PA), resonance-enhanced multiphoton ionization spectra (REMPI), stimulated Raman transfer (SRT) spectra) are of major current interest. This manuscript summarizes the significant level of understanding of these various spectroscopies, enabled by using simple graphical and semiclassical ideas and shortcuts. Physical

Research paper thumbnail of Spectroscopy and applications of the 3 3Σ+ electronic state of 39K85Rb

The Journal of Chemical Physics, 2013

We report new results on the spectroscopy of the 3 (3)Σ(+) electronic state of (39)K(85)Rb. The o... more We report new results on the spectroscopy of the 3 (3)Σ(+) electronic state of (39)K(85)Rb. The observations are based on resonance-enhanced multiphoton ionization of ultracold KRb molecules starting in vibrational levels v'' = 18-23 of the a (3)Σ(+) state and ionized via the intermediate 3 (3)Σ(+) state. The a-state ultracold molecules are formed by photoassociation of ultracold (39)K and (85)Rb atoms to the 3(0(+)) state of KRb followed by spontaneous emission. We discuss the potential applications of this state to future experiments, as a pathway for populating the lowest vibrational levels of the a state as well as the X state.

Research paper thumbnail of Spectroscopy of the double minimum 3 3ΠΩ electronic state of 39K85Rb

The Journal of Chemical Physics, 2013

We report the observation and analysis of the 3 (3)ΠΩ double-minimum electronic excited state of ... more We report the observation and analysis of the 3 (3)ΠΩ double-minimum electronic excited state of (39)K(85)Rb. The spin-orbit components (0(+), 0(-), 1, and 2) of this state are investigated based on potentials developed from the available ab initio potential curves. We have assigned the vibrational levels v' = 2-11 of the 3 (3)Π1,2 potentials and v' = 2-12 of the 3(3)Π0(+/-) potential. We compare our experimental observations of the 3 (3)ΠΩ state with predictions based on theoretical potentials. The observations are based on resonance enhanced multiphoton ionization of ultracold KRb in vibrational levels v" = 14-25 of the a (3)Σ(+) state. These a-state ultracold molecules are formed by photoassociation of ultracold (39)K and (85)Rb atoms to the 5(1) state of KRb followed by spontaneous emission to the a state.

Research paper thumbnail of Resonant Coupling in the Heteronuclear Alkali Dimers for Direct Photoassociative Formation of X(0,0) Ultracold Molecules

The Journal of Physical Chemistry A, 2010

Promising pathways for photoassociative formation of ultracold heteronuclear alkali metal dimers ... more Promising pathways for photoassociative formation of ultracold heteronuclear alkali metal dimers in their lowest rovibronic levels (denoted X(0,0)) are examined using high quality ab initio calculations of potential energy curves currently available. A promising pathway for KRb, involving the resonant coupling of the 2 1 Π and 1 1 Π states just below the lowest excited asymptote (K(4s)+Rb(5p 1/2 )), is found to occur also for RbCs and less promisingly for KCs as well. The resonant coupling of the 3 1 Σ + and 1 1 Π states, also just below the lowest excited asymptote, is found to be promising for LiNa, LiK, LiRb, and less promising for LiCs and KCs. Direct photoassociation to the 1 1 Π state near dissociation appears promising in the final dimers, NaK, NaRb, and NaCs, although detuning more than 100 cm −1 below the lowest excited asymptote may be required.