Difference between revisions of "Mixture Analysis"

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(The Set Up)
 
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== Patterson research group ==
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[http://projects.iq.harvard.edu/pattersongroup Link to the Patterson research group homepage]
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== About The Mixture Analysis Experiment ==
 
== About The Mixture Analysis Experiment ==
The cooling of large molecules and biomolecules is a relatively unexplored area of cold molecular physics. It was recently demonstrated that napthalene, a two ring hydrocarbon, can be effectively cooled via buffer gas cooling. The upper bound on the size and complexity of molecules which can be effectively cooled by buffer gas cooling is unknown. We are exploring techniques for cooling these large molecules as well as collisional physics of large molecules in the gas phase.
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The cooling of large molecules, including biomolecules is a relatively unexplored area of cold molecular physics.  
  
A powerful application of buffer gas cooling of large molecules is in precision spectroscopy. Absorption spectra of large molecules are broad and unpredictable. When large molecules are vibrationally and rotationally cooled, their absorption spectra become very sharp. Recent experiments have demonstrated that electronic structure and corresponding vibrational manifolds can be readily resolved at cryogenic temperatures. Furthermore, arbitrary mixtures of large molecules can be effectively cooled via buffer gas cooling. Current research is focused on spectroscopically identifying constitutions of a complex mixture. Currently, a tunable OPO laser is used to identify features across an arbitrary region of the spectrum. Future research will focus on microwave spectroscopy, which may yield higher signal-to-noise ratios and the possibility of fast Fourier Transform Spectroscopy.
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The vast majority of experiments with larger, cold molecules have come from supersonic jets; since it was developed in the late 1970s, these jets have proven to be a versatile workhorse, producing cold samples of thousands of molecular species.  Although these samples are cold, the samples are in general moving very rapidly in the lab frame and expanding rapidly.  In contrast, buffer gas cooled samples are at or near rest in the lab frame; in addition, if a molecule in a buffer gas is excited, it has a high probability of being 'recycled' back to the ground state via collisions with the buffer gas.  These advantages suggest that buffer gas cooled samples provide an attractive and sensitive alternative to supersonic jets for certain classes of spectroscopic studies.
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We recently demonstrated that naphthalene, a two ring aromatic hydrocarbon, can be efficiently cooled via buffer gas cooling. The upper bound on the size and complexity of molecules which can be effectively cooled by buffer gas cooling is unknown. We are exploring techniques for cooling these large molecules as well as the collisional physics of large molecules in the gas phase.
 +
 
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A powerful application of buffer gas cooling of large molecules is in broadband, high resolution spectroscopy. UV-visible absorption spectra of large molecules are in general composed of broad, unresolvable manifolds of thousands of ro-vibrational lines. When large molecules are vibrationally and rotationally cooled, their absorption spectra become greatly simplified. If a complex mixture of many such molecules could be efficiently cooled, UV-visible or microwave spectroscopy could effectively resolved, even if the mixture was composed of thousands of a-priori unknown components. Early results suggest that arbitrary mixtures of large molecules can be effectively cooled via buffer gas cooling.
 +
 
 +
Current research is focused on developing techniques to spectroscopically identify constitutions of a complex mixture. Currently, laser induced fluorescence excited by a widely tunable OPO laser is used to identify features across an arbitrary region of the spectrum.  This system provides a flexible testbed for cooling a large number of molecular species and mixtures. Future experimental possibilities include single and double resonance microwave spectroscopy, UV-visible and NIR fourier transform spectroscopy, and integration with gas chromatography to pre-separate the mixture.
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== Measuring Chirality ==
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<html><iframe width="480" height="293" src="//www.youtube.com/embed/qonwuQLXjPI" frameborder="0" allowfullscreen></iframe></html>
  
 
== The Set Up ==
 
== The Set Up ==
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== People ==
 
== People ==
 
* Garrett Drayna
 
 
* Dave Patterson
 
* Dave Patterson
* Edem Tsikata (Now a postdoc at [http://www.jpl.nasa.gov/ JPL])
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* Melanie Schnell @CFEL(http://mpg.cfel.de/asg/sdccm/)
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* Edem Tsikata (Now a Research Fellow at [http://connects.catalyst.harvard.edu/Profiles/display/Person/121368 Massachusetts Eye and Ear Infirmary])
  
 
== Publications ==
 
== Publications ==
  
 
* [[Media:Napthalene_pccp.pdf‎|Cooling and Collisions of Large Gas Phase Molecules.]]  D. Patterson, E. Tsikita, and J.M. Doyle. Phys Chem Chem Phys. 12(33), 9736-41 (2010)
 
* [[Media:Napthalene_pccp.pdf‎|Cooling and Collisions of Large Gas Phase Molecules.]]  D. Patterson, E. Tsikita, and J.M. Doyle. Phys Chem Chem Phys. 12(33), 9736-41 (2010)

Latest revision as of 10:18, 7 November 2016

Patterson research group

Link to the Patterson research group homepage

About The Mixture Analysis Experiment

The cooling of large molecules, including biomolecules is a relatively unexplored area of cold molecular physics.

The vast majority of experiments with larger, cold molecules have come from supersonic jets; since it was developed in the late 1970s, these jets have proven to be a versatile workhorse, producing cold samples of thousands of molecular species. Although these samples are cold, the samples are in general moving very rapidly in the lab frame and expanding rapidly. In contrast, buffer gas cooled samples are at or near rest in the lab frame; in addition, if a molecule in a buffer gas is excited, it has a high probability of being 'recycled' back to the ground state via collisions with the buffer gas. These advantages suggest that buffer gas cooled samples provide an attractive and sensitive alternative to supersonic jets for certain classes of spectroscopic studies.

We recently demonstrated that naphthalene, a two ring aromatic hydrocarbon, can be efficiently cooled via buffer gas cooling. The upper bound on the size and complexity of molecules which can be effectively cooled by buffer gas cooling is unknown. We are exploring techniques for cooling these large molecules as well as the collisional physics of large molecules in the gas phase.

A powerful application of buffer gas cooling of large molecules is in broadband, high resolution spectroscopy. UV-visible absorption spectra of large molecules are in general composed of broad, unresolvable manifolds of thousands of ro-vibrational lines. When large molecules are vibrationally and rotationally cooled, their absorption spectra become greatly simplified. If a complex mixture of many such molecules could be efficiently cooled, UV-visible or microwave spectroscopy could effectively resolved, even if the mixture was composed of thousands of a-priori unknown components. Early results suggest that arbitrary mixtures of large molecules can be effectively cooled via buffer gas cooling.

Current research is focused on developing techniques to spectroscopically identify constitutions of a complex mixture. Currently, laser induced fluorescence excited by a widely tunable OPO laser is used to identify features across an arbitrary region of the spectrum. This system provides a flexible testbed for cooling a large number of molecular species and mixtures. Future experimental possibilities include single and double resonance microwave spectroscopy, UV-visible and NIR fourier transform spectroscopy, and integration with gas chromatography to pre-separate the mixture.

Measuring Chirality

The Set Up

The 1st generation Mixture Analysis Experiment.

People

Publications