Raman microscope - Revision history

Cmditradmin: /* Overview */

2011-10-10T22:12:29Z

Overview

← Older revision		Revision as of 15:12, 10 October 2011
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	=== Overview ===		=== Overview ===
	[[Image:Ramanspec.jpg\|thumb\|300px\| The confocal nature of the Raman micrsocope allows you to probe different layers]]		[[Image:Ramanspec.jpg\|thumb\|300px\| The confocal nature of the Raman micrsocope allows you to probe different layers]]
	The Raman microscope is an optical microscope through which an monochromatic laser source is directed at a sample. The sample absorbs energy and scatters the light at different wavelengths which is then read with a CCD camera. Raman is based inelastic scattering due to characteristic vibrational modes of the material being studied. It is an sensitive spectroscopic technique which allows you to no destructively identify microscopic samples.		The Raman microscope is an optical microscope through which a monochromatic laser source is directed at a sample. The sample absorbs energy and scatters the light at different wavelengths which is then read with a CCD camera. Raman is based inelastic scattering due to characteristic vibrational modes of the material being studied. It is a sensitive spectroscopic technique which allows you to no destructively identify microscopic samples.

	[[Image:Raman energy levels.svg\|thumb\|300px\|Energy level diagram showing the states involved in Raman signal. The line thickness is roughly proportional to the signal strength from the different transitions.]]		[[Image:Raman energy levels.svg\|thumb\|300px\|Energy level diagram showing the states involved in Raman signal. The line thickness is roughly proportional to the signal strength from the different transitions.]]

Cmditradmin: /* Significance */

2011-10-03T19:37:01Z

Significance

← Older revision		Revision as of 12:37, 3 October 2011
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	=== Significance ===		=== Significance ===
	Graphene is a carbon containing material with sp2 hybridization. It ~~started off in this case started as~~ exfoliated graphene from a highly ordered pyroforic graphene block and ~~we used~~ the scotch tape method to flake off individual layers until ~~we have~~ single level of graphene. Using the Raman microscope we optically probe the material to see if it is graphene, two layer graphene or graphite graphene		Graphene is a carbon containing material with sp2 hybridization. It can be made from exfoliated graphene from a highly ordered pyroforic graphene block and using the scotch tape method to flake off individual layers until there is a single level of graphene. Using the Raman microscope we optically probe the material to see if it is graphene, two layer graphene or graphite graphene

	Raman is a non-linear application and it follows closely with IR absorption spectroscopy. In the dipole expression the absorption is dependent on the dipole moment. The first term in the dipole expression is the permanent dipole moment which is used for infrared absorption. So we go between vibrational energy levels with a photon of energy tuned to the gap between. If you want to have infrared absorption you need a permanent dipole moment.		Raman is a non-linear application and it follows closely with IR absorption spectroscopy. In the dipole expression the absorption is dependent on the dipole moment. The first term in the dipole expression is the permanent dipole moment which is used for infrared absorption. So we go between vibrational energy levels with a photon of energy tuned to the gap between. If you want to have infrared absorption you need a permanent dipole moment.

Cmditradmin: /* Operation */

2011-09-29T21:19:23Z

Operation

← Older revision		Revision as of 14:19, 29 September 2011
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	=== Operation ===		=== Operation ===
	{{#ev:youtube\|~~oLbjK72ix-0~~}}		{{#ev:youtube\|T5z2M3vxyH8}}

	=== External links ===		=== External links ===

Cmditradmin: /* Significance */

2011-09-22T17:42:33Z

Significance

← Older revision		Revision as of 10:42, 22 September 2011
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	IR spectroscopy and Raman spectroscopy are complementary; based on the rules of symmetry there are IR modes which are Raman inactive, and Raman modes which are IR inactive. Water is an IR absorbing material which limits the ability to study wet samples with IR spectroscopy. But water has a weak Raman absorption so we can use Raman to study wet materials or cells in growth media.		IR spectroscopy and Raman spectroscopy are complementary; based on the rules of symmetry there are IR modes which are Raman inactive, and Raman modes which are IR inactive. Water is an IR absorbing material which limits the ability to study wet samples with IR spectroscopy. But water has a weak Raman absorption so we can use Raman to study wet materials or cells in growth media.
			<div id="Flash">Selection Rules for Raman and IR</div>

	<swf width=500 height=400>/images/9/9f/Vibrations_simp.swf</swf>		<swf width=500 height=400>/images/9/9f/Vibrations_simp.swf</swf>

Cmditradmin: /* Significance */

2011-09-22T17:39:56Z

Significance

← Older revision		Revision as of 10:39, 22 September 2011
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	IR spectroscopy and Raman spectroscopy are complementary; based on the rules of symmetry there are IR modes which are Raman inactive, and Raman modes which are IR inactive. Water is an IR absorbing material which limits the ability to study wet samples with IR spectroscopy. But water has a weak Raman absorption so we can use Raman to study wet materials or cells in growth media.		IR spectroscopy and Raman spectroscopy are complementary; based on the rules of symmetry there are IR modes which are Raman inactive, and Raman modes which are IR inactive. Water is an IR absorbing material which limits the ability to study wet samples with IR spectroscopy. But water has a weak Raman absorption so we can use Raman to study wet materials or cells in growth media.

	<swf width=500 height=400>/images/6/6b/~~Vibrations~~.swf</swf>		<swf width=500 height=400>/images/9/9f/Vibrations_simp.swf</swf>

	Raman is an inelastic scattering event. It uses a photon with high energy with respect to vibrational energy levels but low energy with respect to electronic transition. IR absorption is the absorption of a photon equivalent to the gap between vibrational energy levels. If we increase the energy we can get a a absorbed photon in the UV-Vis spectra that transitions between the ground level and the first excited state.		Raman is an inelastic scattering event. It uses a photon with high energy with respect to vibrational energy levels but low energy with respect to electronic transition. IR absorption is the absorption of a photon equivalent to the gap between vibrational energy levels. If we increase the energy we can get a a absorbed photon in the UV-Vis spectra that transitions between the ground level and the first excited state.

Cmditradmin: /* External links */

2011-09-19T23:31:39Z

External links

← Older revision		Revision as of 16:31, 19 September 2011
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	*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]		*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]

	*[[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/ChemWiki_Module_Topics/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]]		*[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/ChemWiki_Module_Topics/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]

Cmditradmin: /* External links */

2011-09-19T23:30:59Z

External links

← Older revision		Revision as of 16:30, 19 September 2011
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	*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]		*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]

	*[[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/~~ChemWiki_Module_Topic~~/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]]		*[[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/ChemWiki_Module_Topics/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]]

Cmditradmin: /* External links */

2011-09-19T23:29:33Z

External links

← Older revision		Revision as of 16:29, 19 September 2011
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	*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]		*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]

	*[[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/~~ChemWiki_Module_Topics~~/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]]		*[[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/ChemWiki_Module_Topic/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]]

Cmditradmin: /* External links */

2011-09-19T23:28:53Z

External links

← Older revision		Revision as of 16:28, 19 September 2011
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	*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]		*[[wikipedia:Infrared_spectroscopy IR spectroscopy vibrational modes]]

			*[[http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3A_Kauzlarich/ChemWiki_Module_Topics/Number_of_vibrational_modes_for_a_molecule UC Davis Chemwiki on Vibrational modes]]

Cmditradmin: /* Significance */

2011-09-19T23:14:29Z

Significance

← Older revision		Revision as of 16:14, 19 September 2011
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	Raman is a non-linear application and it follows closely with IR absorption spectroscopy. In the dipole expression the absorption is dependent on the dipole moment. The first term in the dipole expression is the permanent dipole moment which is used for infrared absorption. So we go between vibrational energy levels with a photon of energy tuned to the gap between. If you want to have infrared absorption you need a permanent dipole moment.		Raman is a non-linear application and it follows closely with IR absorption spectroscopy. In the dipole expression the absorption is dependent on the dipole moment. The first term in the dipole expression is the permanent dipole moment which is used for infrared absorption. So we go between vibrational energy levels with a photon of energy tuned to the gap between. If you want to have infrared absorption you need a permanent dipole moment.
	In an aromatic compound such as benzene there is athere are lots of delocalized electrons but there is not permanent dipole moment so it has no infrared absorption. Therefore this it is useful to use non-linear spectroscopy in which we examine the strength of the induced dipole in an electric field. Benzene has an extremely strong Raman signal. IR spectroscopy and Raman spectroscopy are complementary; based on the rules of symmetry there are IR modes which are Raman inactive, and Raman modes which are IR inactive. Water is an IR absorbing material which limits the ability to study wet samples with IR spectroscopy. But water has a weak Raman absorption so we can use Raman to study wet materials or cells in growth media.

			In an aromatic compound such as benzene there are lots of delocalized electrons but there is not permanent dipole moment so it has no infrared absorption. Therefore this it is useful to use non-linear spectroscopy in which we examine the strength of the induced dipole in an electric field. Benzene has an extremely strong Raman signal.

			IR spectroscopy and Raman spectroscopy are complementary; based on the rules of symmetry there are IR modes which are Raman inactive, and Raman modes which are IR inactive. Water is an IR absorbing material which limits the ability to study wet samples with IR spectroscopy. But water has a weak Raman absorption so we can use Raman to study wet materials or cells in growth media.

			<swf width=500 height=400>/images/6/6b/Vibrations.swf</swf>

	Raman is an inelastic scattering event. It uses a photon with high energy with respect to vibrational energy levels but low energy with respect to electronic transition. IR absorption is the absorption of a photon equivalent to the gap between vibrational energy levels. If we increase the energy we can get a a absorbed photon in the UV-Vis spectra that transitions between the ground level and the first excited state.		Raman is an inelastic scattering event. It uses a photon with high energy with respect to vibrational energy levels but low energy with respect to electronic transition. IR absorption is the absorption of a photon equivalent to the gap between vibrational energy levels. If we increase the energy we can get a a absorbed photon in the UV-Vis spectra that transitions between the ground level and the first excited state.