In this thesis, direct cooling of gaseous formaldehyde (H2CO) to the ultracold regime (T < 1 mK) is experimentally demonstrated. Employing optoelectrical Sisyphus cooling, a dissipative cooling method applicable to electrically trapped dipolar molecules, an ensemble of about 300,000 molecules with a temperature of around 400 µK is generated. More than 80% of these molecules populate a single rotational state. These results are used to implement a technique for high-resolution spectroscopy on electrically trapped molecules.In this thesis, direct cooling of gaseous formaldehyde (H2CO) to the ultracold regime (T < 1 mK) is experimentally demonstrated. Employing optoelectrical Sisyphus cooling, a dissipative cooling method applicable to electrically trapped dipolar molecules, an ensemble of about 300,000 molecules with a temperature of around 400 µK is generated. More than 80% of these molecules populate a single rotational state. These results are used to implement a technique for high-resolution spectroscopy on electrically trapped molecules.

Jan 1, 20181 citation

Ultracold Molecules: Production and Application

S. Inouye

Springer series in chemical physicsJan 1, 20171 citation

Internal-state thermometry by depletion spectroscopy in a cold guided beam of formaldehyde

M. Motsch, Markus Schenk, L. D. van Buuren +3 more

We present measurements of the internal state distribution of electrostatically guided formaldehyde. Upon excitation with continuous tunable ultraviolet laser light the molecules dissociate, leading to a decrease in the molecular flux. The population of individual guided states is measured by addressing transitions originating from them. The measured populations of selected states show good agreement with theoretical calculations for different temperatures of the molecule source. The purity of the guided beam as deduced from the entropy of the guided sample using a source temperature of $150\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ corresponds to that of a thermal ensemble with a temperature of about $30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ .We present measurements of the internal state distribution of electrostatically guided formaldehyde. Upon excitation with continuous tunable ultraviolet laser light the molecules dissociate, leading to a decrease in the molecular flux. The population of individual guided states is measured by addressing transitions originating from them. The measured populations of selected states show good agreement with theoretical calculations for different temperatures of the molecule source. The purity of the guided beam as deduced from the entropy of the guided sample using a source temperature of $150\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ corresponds to that of a thermal ensemble with a temperature of about $30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

arXiv:0710.3316Physical Review ADec 20, 200724 citations

Production of cold formaldehyde molecules for study and control of chemical reaction dynamics with hydroxyl radicals

Eric R. Hudson, Christopher Ticknor, Brian C. Sawyer +5 more

We propose a method for controlling a class of low temperature chemical reactions. Specifically, we show the hydrogen abstraction channel in the reaction of formaldehyde $({\mathrm{H}}_{2}\mathrm{CO})$ and the hydroxyl radical $(\mathrm{OH})$ can be controlled through either the molecular state or an external electric field. We also outline experiments for investigating and demonstrating control over this important reaction. To this end, we report the first Stark deceleration of ${\mathrm{H}}_{2}\mathrm{CO}$ . We have decelerated a molecular beam of ${\mathrm{H}}_{2}\mathrm{CO}$ essentially to rest, producing molecules at $100\phantom{\rule{0.3em}{0ex}}\mathrm{mK}$ with a density of $\ensuremath{\sim}{10}^{6}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$.We propose a method for controlling a class of low temperature chemical reactions. Specifically, we show the hydrogen abstraction channel in the reaction of formaldehyde $({\mathrm{H}}_{2}\mathrm{CO})$ and the hydroxyl radical $(\mathrm{OH})$ can be controlled through either the molecular state or an external electric field. We also outline experiments for investigating and demonstrating control over this important reaction. To this end, we report the first Stark deceleration of ${\mathrm{H}}_{2}\mathrm{CO}$. We have decelerated a molecular beam of ${\mathrm{H}}_{2}\mathrm{CO}$ essentially to rest, producing molecules at $100\phantom{\rule{0.3em}{0ex}}\mathrm{mK}$ with a density of $\ensuremath{\sim}{10}^{6}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$.

arXiv:physics/0508120Physical Review AJun 6, 2006118 citations

Chemistry at ultracold temperatures

N. Balakrishnan, A. Dalgarno

Chemical Physics LettersJun 1, 2001246 citations

150\phantom{\rule{0.3em}{0ex}}\mathrm{K}

corresponds to that of a thermal ensemble with a temperature of about

30\phantom{\rule{0.3em}{0ex}}\mathrm{K}

We propose a method for controlling a class of low temperature chemical reactions. Specifically, we show the hydrogen abstraction channel in the reaction of formaldehyde

({\mathrm{H}}_{2}\mathrm{CO})

and the hydroxyl radical

(\mathrm{OH})

can be controlled through either the molecular state or an external electric field. We also outline experiments for investigating and demonstrating control over this important reaction. To this end, we report the first Stark deceleration of

{\mathrm{H}}_{2}\mathrm{CO}

. We have decelerated a molecular beam of

{\mathrm{H}}_{2}\mathrm{CO}

essentially to rest, producing molecules at

100\phantom{\rule{0.3em}{0ex}}\mathrm{mK}

with a density of $\ensuremath{\sim}{10}^{6}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$.