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9 results on '"Schwanke, Erik"'

1. Laser and Fourier transform spectroscopy of KCa

Author

Gerschmann, Julia, Schwanke, Erik, Pashov, Asen, Knöckel, Horst, Ospelkaus, Silke, and Tiemann, Eberhard

Subjects
Physics - Atomic Physics
Abstract

KCa was produced in a heatpipe oven and its thermal emission spectrum around 8900 cm$^{-1}$ was recorded by a high resolution Fourier transform spectrometer. In addition, many selected transitions of this spectrum between deeply bound vibrational levels of the $\mathrm{X}(1)^2\Sigma^+$ and $(2)^2\Sigma^+$ states were studied using laser excitation to facilitate the assignment of the lines. The ground state is described for $v^{\prime\prime} =$ 0 - 5 and the $(2)^2\Sigma^+$ state for $v^{\prime} =0$ - 8 with rotational levels up to 175. For both states, Dunham coefficients, spin-rotation parameters and potential energy curves are derived., Comment: 9 pages, 8 figures

Published
2017
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2. Laser and Fourier transform spectroscopy of $^7$Li$^{88}$Sr

Author

Schwanke, Erik, Knöckel, Horst, Pashov, Asen, Stein, Alexander, Ospelkaus, Silke, and Tiemann, Eberhard

Subjects
Physics - Atomic Physics
Abstract

LiSr was produced in a heat-pipe oven and its thermal emission spectrum around 9300 cm$^{-1}$ was recorded by a high resolution Fourier transform spectrometer. In addition, selected lines of the spectrum of deeply bound vibrational levels of the $1^2\Sigma^+$ and $2^2\Sigma^+$ states were studied using laser excitation to facilitate the assignment of the lines. The ground state could be described for $v^{\prime\prime} =$ 0 - 2, $N^{\prime\prime}$ up to 105 and the $2^2\Sigma^+$ state for $v^{\prime} = 0$ up to $N^\prime = 68$. For both states, Dunham coefficients, spin-rotation parameters and potential energy curves were evaluated. A coupling of the $2^2\Sigma^+$ state to the $1^2\Pi$ state was observed, allowing a local description with Dunham coefficients of the $1^2\Pi$ state and an approximate evaluation of the coupling strength., Comment: 8 pages, 7 figures

Published
2017
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3. The electronic system (2)2Σ+ and (1)2Π of LiCa.

Author

Gerschmann, Julia, Schwanke, Erik, Ospelkaus, Silke, and Tiemann, Eberhard

Subjects
*FOURIER transform spectroscopy, *ELECTRONIC systems, *SPIN-orbit coupling constants, *FLUORESCENCE spectroscopy, *ANALYTIC functions, *INFRARED lasers
Abstract

High-resolution Fourier transform spectroscopy and Laser-induced fluorescence have been performed on LiCa in the infrared spectral range. We analyse rovibrational transitions of the (2) 2 Σ + – X (1) 2 Σ + system of LiCa and find the (2) 2 Σ + state to be perturbed by spin–orbit coupling to the (1) 2 Π state. We study the coupled system obtaining molecular parameters for the (2) 2 Σ + and the (1) 2 Π state together with effective spin–orbit and spin–rotation coupling constants. The coupled system has also been evaluated by applying a potential function instead of rovibrational molecular parameters for the state (2) 2 Σ + . An improved analytic potential function of the X (1) 2 Σ + state is derived, due to the extension of the observed rotational ladder. [ABSTRACT FROM AUTHOR]

Published
2023
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5. The coupled system (2)2Σ+ and (1)2Π of 7Li88Sr

Author

Schwanke, Erik, Gerschmann, Julia, Knöckel, Horst, Ospelkaus, Silke, and Tiemann, Eberhard

Subjects
potential energy surfaces, Mass spectrometry, Rotation, Vibrational levels, Vibration analysis, Molecular spectra, Rovibrational transitions, Lithium alloys, Excited states, Molecular parameters, Binary alloys, Molecular spectroscopy, Vibration rotations, Potential energy, Rovibrational levels, Dunham coefficients, ddc:530, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Molecular coupling, Strontium alloys, vibration and vibration-rotation constants, Quantum chemistry
Abstract

We analyse rovibrational transitions of the (2)2Σ+-X(1)2Σ+ system of LiSr and find the energy levels of the (2)2Σ+ state to be perturbed by coupling between the (2)2Σ+ and (1)2Π states. We present an analysis of the coupled system yielding molecular parameters for the lowest vibrational levels of the (2)2Σ+ state and for higher vibrational levels of the (1)2Π state together with molecular coupling constants. Improved Dunham coefficients for the rovibrational levels of the X(1)2Σ+ state are also obtained, where the correlation with the parameters of the excited states is removed completely. © 2020 The Author(s). Published by IOP Publishing Ltd.

Published
2020

7. Spectroscopic investigation of the three lowest doublet states of LiSr

Author

Schwanke, Erik

Subjects
alkali-alkaline earth-molecules, ddc:530, molecular spectrum, Alkali-Erdalkali-Moleküle, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Optische Spektroskopie, optical spectroscopy, Molekülspektrum
Abstract

Molecules consisting of an alkali and an alkaline earth atom are currently investigated with the aim of using them in experiments to explore diverse physical phenomena. This thesis is concerned with the observation and analysis of the infrared spectrum of LiSr in the gas phase. The moderate reduced mass of LiSr implies a relatively low density of the thermal emission lines. Individual transition lines can be discerned in the spectrum and enable the tracing of rotational branches in the thermal emission spectrum. An analysis of the thermal emission spectrum of LiSr is presented. The spectrum displays clearly visible vibrational bands. Their line structure shows two distinguishable rotational systems due to spin-rotation coupling. A method to readily find the assignment of rotational quantum numbers by using laser radiation to excite the molecular sample at different frequencies is demonstrated. Using the thermal emission spectrum together with laser-induced fluorescence spectra from dfferent laser experiments allowed a thorough description of the rotational energy ladders of the lowest vibrational states v′′ = 0, 1, 2 and v′ = 0, 1 of the (2)2Σ+–X(1)2Σ+ system. It was found that several large perturbations occur in the (2)2Σ+ state. These perturbations are attributed to a coupling of the (2)2Σ+ to the (1)2Π and a model to describe the coupled system is established here, which includes a description of a few vibrational levels in the (1)2Π state., Zweiatomige Moleküle mit einem Alkali- und einem Erdalkaliatom werden derzeit untersucht, um sie in späteren Experimenten zur Erforschung verschiedener physikalischer Phänomene zu nutzen. Diese Arbeit beschreibt die Aufnahme und Interpretation des nahinfraroten Spektrums eines Gases von LiSr-Molekülen. Die geringe reduzierte Masse von LiSr bedingt eine vergleichsweise geringe Liniendichte im thermischen Emissionsspektrum. Das thermische Emissionsspektrum wird ausführlich besprochen. Es zeigt deutliche Vibrationsbanden, die aufgrund der Spin-Rotationskopplung zwei unterschiedliche Rotationsspektren erkennen lassen. Weiterhin wird eine Methode zur schnellen Zuordnung von Rotationsquantenzahlen vorgestellt, die durch die Verwendung von Laserstrahlung zur gezielten Anregung der Moleküle ermöglicht wird. Die Zusammenführung des thermischen Emissionsspektrums mit den Spektren verschiedener Laserexperimente erlaubt eine umfassende Beschreibung der Rotationsleitern der niedrigsten Vibrationszustände v′′ = 0, 1, 2 und v′ = 0, 1 des (2)2Σ+–X(1)2Σ+ -Systems. Im (2)2Σ+ -Zustand wurden mehrere starke Störungen gefunden, die einer Kopplung zwischen den (2)2Σ+ - und (1)2Π-Zuständen zugeschrieben werden. Ein Modell zur Beschreibung dieses gekoppelten Systems wird entwickelt. Hiermit wird auch eine Beschreibung einiger Vibrationsniveaus des (1)2Π-Zustandes erreicht.

Published
2019
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