Introduction to Absorption - Revision history

Knoone: /* Plank's relation */

2010-06-15T23:07:19Z

Plank's relation

← Older revision		Revision as of 16:07, 15 June 2010
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	== Plank's relation ==		== Plank's relation ==

	Light can be characterized in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s .		Light can be characterized in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s.

	In the early 20th century, Planck showed that the energy of a photon can be related to its frequency by using the Planck relation (also called the Planck-Einstein equation)		In the early 20th century, Planck showed that the energy of a photon can be related to its frequency by using the Planck relation (also called the Planck-Einstein equation)

Knoone at 22:16, 15 June 2010

2010-06-15T22:16:29Z

← Older revision		Revision as of 15:16, 15 June 2010
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	Absorption of electromagnetic radiation (light) occurs when the energy of a photon is transferred to matter. Absorption can occur in atoms by promoting an electron to higher energetic states. In molecules, absorption can result from transitions into higher electronic, vibrational, and rotational states.		Absorption of electromagnetic radiation (light) occurs when the energy of a photon is transferred to matter. Absorption can occur in atoms by promoting an electron to higher energetic states. In molecules, absorption can result from transitions into higher electronic, vibrational, and rotational states. The absorption of light is fundamental process relevant to many photonics materials and devices.

	== Plank's relation ==		== Plank's relation ==

Knoone at 22:14, 15 June 2010

2010-06-15T22:14:48Z

← Older revision		Revision as of 15:14, 15 June 2010
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	~~The absorption~~ of light is ~~fundamental process that ties together all aspects of photonics materials~~ and ~~devices~~.		Absorption of electromagnetic radiation (light) occurs when the energy of a photon is transferred to matter. Absorption can occur in atoms by promoting an electron to higher energetic states. In molecules, absorption can result from transitions into higher electronic, vibrational, and rotational states.
	=== Plank's relation ===
			== Plank's relation ==

	Light can be characterized in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s .		Light can be characterized in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s .
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	Thus, the energy of the light is directly proportional to its frequency and inversely proportional to its wavelength. One distinction that is important to understand is that the energy of light as a function of a frequency and also the field strength of light . The strength of the field of light is called the intensity of light. If it is very intense and you look into it, it can blind you. The energy we are discussing here is the energy of a photon. If there is a ground state and an excited state, there will be a certain wavelength of light that is required in order to achieve an absorption by the molecule.		Thus, the energy of the light is directly proportional to its frequency and inversely proportional to its wavelength. One distinction that is important to understand is that the energy of light as a function of a frequency and also the field strength of light . The strength of the field of light is called the intensity of light. If it is very intense and you look into it, it can blind you. The energy we are discussing here is the energy of a photon. If there is a ground state and an excited state, there will be a certain wavelength of light that is required in order to achieve an absorption by the molecule.

	=== Excitation vs polarization ===		== Excitation vs polarization ==

	A molecule can interact with light and light can be absorbed. There is a transition with a starting state and a final state. These lines the HOMO of the molecule to the LUMO of the molecule. A beam of light excites the molecule causing one electron to jump from the HOMO (a filled orbital) to the LUMO (an unfilled orbital). This is a simple one electron picture. If there is a true absorption of a photon, this state will have a finite lifetime. That means that after the electric field is removed, (i.e the light is shut off,) the molecule will be metastable in that state and will come back down to the ground state with a certain characteristic lifetime. Even if the light does not have enough energy to promote an electron from one level to another, it can still get the electrons in the molecule to resonate back and forth and oscillate; this process is referred to as polarization. However, as soon as that field is removed, the molecule will be instantaneously back in its ground state.		A molecule can interact with light and light can be absorbed. There is a transition with a starting state and a final state. These lines the HOMO of the molecule to the LUMO of the molecule. A beam of light excites the molecule causing one electron to jump from the HOMO (a filled orbital) to the LUMO (an unfilled orbital). This is a simple one electron picture. If there is a true absorption of a photon, this state will have a finite lifetime. That means that after the electric field is removed, (i.e the light is shut off,) the molecule will be metastable in that state and will come back down to the ground state with a certain characteristic lifetime. Even if the light does not have enough energy to promote an electron from one level to another, it can still get the electrons in the molecule to resonate back and forth and oscillate; this process is referred to as polarization. However, as soon as that field is removed, the molecule will be instantaneously back in its ground state.
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	=== Solvent effects ===		== Solvent effects ==

	The Planck relation tells us exactly what energy is required of the photon to get the promotion of an electron from a ground state to an excited state.		The Planck relation tells us exactly what energy is required of the photon to get the promotion of an electron from a ground state to an excited state.
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	=== Energy Units ===		== Energy Units ==

	There are different units of energy used to characterize photon energies and all energies. This is very important to understand because it helps you move along between the language of physics, language of chemistry, and the language of spectroscopy. The units of energy are:		There are different units of energy used to characterize photon energies and all energies. This is very important to understand because it helps you move along between the language of physics, language of chemistry, and the language of spectroscopy. The units of energy are:

Knoone: /* Plank's relation */

2010-06-15T21:30:40Z

Plank's relation

← Older revision		Revision as of 14:30, 15 June 2010
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	=== Plank's relation ===		=== Plank's relation ===

	We can ~~characterize light~~ in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s .		Light can be characterized in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s .

	In the early 20th century, Planck showed that the energy of a photon can be related to its frequency by using the Planck relation (also called the Planck-Einstein equation)		In the early 20th century, Planck showed that the energy of a photon can be related to its frequency by using the Planck relation (also called the Planck-Einstein equation)

Knoone: /* Plank's relation */

2010-06-15T21:18:43Z

Plank's relation

← Older revision		Revision as of 14:18, 15 June 2010
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	:<math>E=h \nu\!</math>		:<math>E=h \nu\!</math>

	or, since ~~<math>{C\lambda}~~=c~~!</math>~~:		or, since λν = c:

	:<math>E=\frac {h c}{\lambda} \,\!</math>		:<math>E=\frac {h c}{\lambda} \,\!</math>

Knoone: /* Plank's relation */

2010-06-15T19:45:52Z

Plank's relation

← Older revision		Revision as of 12:45, 15 June 2010
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	=== Plank's relation ===		=== Plank's relation ===

	We can characterize light in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed ~~many years back~~ that the energy of a photon can be related to its frequency by using the ~~Planck’s~~ relation		We can characterize light in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s .

			In the early 20th century, Planck showed that the energy of a photon can be related to its frequency by using the Planck relation (also called the Planck-Einstein equation)

	:<math>E=h \nu\!</math>		:<math>E=h \nu\!</math>

	or		or, since <math>{C\lambda}=c!</math>:

	:<math>E=\frac {h c}{\lambda} \,\!</math>		:<math>E=\frac {h c}{\lambda} \,\!</math>

Knoone: /* Plank's relation */

2010-06-15T19:32:11Z

Plank's relation

← Older revision		Revision as of 12:32, 15 June 2010
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	=== Plank's relation ===		=== Plank's relation ===

	We can characterize light in multiple ways~~. Light can be characterized~~ by its frequency, which is the number of oscillations per second, ~~and~~ its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed many years back that the energy of a photon can be related to its frequency by using the Planck’s relation		We can characterize light in multiple ways, notably, either by its frequency, which is the number of oscillations per second, or its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed many years back that the energy of a photon can be related to its frequency by using the Planck’s relation

	:<math>E=h \nu\!</math>		:<math>E=h \nu\!</math>

Knoone: /* Plank's relation */

2010-06-15T19:31:39Z

Plank's relation

← Older revision		Revision as of 12:31, 15 June 2010
Line 9:		Line 9:
	=== Plank's relation ===		=== Plank's relation ===

	We can characterize light in multiple ways. ~~In a very simple way, light~~ can be characterized by its frequency, which is the number of oscillations per second, and its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed many years back that the energy of a photon can be related to its frequency by using the Planck’s relation		We can characterize light in multiple ways. Light can be characterized by its frequency, which is the number of oscillations per second, and its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed many years back that the energy of a photon can be related to its frequency by using the Planck’s relation

	:<math>E=h \nu\!</math>		:<math>E=h \nu\!</math>

Knoone: /* Plank's relation */

2010-04-28T18:30:20Z

Plank's relation

← Older revision		Revision as of 11:30, 28 April 2010
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	Thus, the energy of the light is ~~the linear function of the~~ frequency, and ~~is also~~ inversely proportional to ~~the~~ wavelength. One distinction that is important to understand is that the energy of light as a function of a frequency and also the field strength of light . The strength of the field of light is called the intensity of light. If it is very intense and you look into it, it can blind you. The energy we are discussing here is the energy of a photon. If there is a ground state and an excited state, there will be a certain wavelength of light that is required in order to achieve an absorption by the molecule.		Thus, the energy of the light is directly proportional to its frequency and inversely proportional to its wavelength. One distinction that is important to understand is that the energy of light as a function of a frequency and also the field strength of light . The strength of the field of light is called the intensity of light. If it is very intense and you look into it, it can blind you. The energy we are discussing here is the energy of a photon. If there is a ground state and an excited state, there will be a certain wavelength of light that is required in order to achieve an absorption by the molecule.

	=== Excitation vs polarization ===		=== Excitation vs polarization ===

Knoone: /* Plank's relation */

2010-04-28T18:29:20Z

Plank's relation

← Older revision		Revision as of 11:29, 28 April 2010
Line 11:		Line 11:
	We can characterize light in multiple ways. In a very simple way, light can be characterized by its frequency, which is the number of oscillations per second, and its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed many years back that the energy of a photon can be related to its frequency by using the Planck’s relation		We can characterize light in multiple ways. In a very simple way, light can be characterized by its frequency, which is the number of oscillations per second, and its wavelength, literally the distance between peaks in a sinosoidal curve. Also, for any wave, the product of its wavelength times its frequency is the speed of that wave. For example, the speed of light traveling in a vacuum is roughly 3x 10^08 m/s . Planck showed many years back that the energy of a photon can be related to its frequency by using the Planck’s relation

	:<math>E=h \nu,\!</math>		:<math>E=h \nu\!</math>

	or		or