Maximum coverage problem: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
rm incorrect definition
 
en>Baldazen
m Known extensions: corrected typo
Line 1: Line 1:
{{context|date=September 2010}}


[[Ligand]] K-edge [[X-ray absorption spectroscopy|XAS]] is a spectroscopic technique that allows the direct study of metal-ligand bonding.<ref>{{Cite doi|10.1016/j.ccr.2004.03.020}}</ref> In a XAS experiment, electrons in ligand 1s orbitals are excited to unfilled p ([[principal quantum number]] n <= 4) and continuum states. This results in a large spectral feature known as a rising edge. Transitions at energies lower than the edge can occur, provided they are to orbitals with some ligand p character, and are called pre-edges. Such transitions are often observed in the data of complexes with metal-ligand bonding.


Latoria is the identify people use to contact me but I hardly ever really preferred that identify. To participate in [http://www.britannica.com/search?query=lacross lacross] is a person of the items I really like most. Kansas is in which we've been dwelling for several years and I have almost everything that I need to have in this article. Reserving vacations has been my job for some time. Go to my web site to come across out more: http://transitionlab.sinnwerkstatt.com/index.php?title=Benutzer_Diskussion:Danuta34Kvddlhv<br><br>Check out my web blog - [http://transitionlab.sinnwerkstatt.com/index.php?title=Benutzer_Diskussion:Danuta34Kvddlhv Zapatillas MBT Precios]
Pre-edge intensities (D<sub>0</sub>) are related to the amount of ligand (L) character in the unfilled orbital:
 
<math>D_0(L \ 1s \rightarrow \psi^*) = const \ \vert \langle L \ 1s \vert \mathbf{r} \vert \psi^* \rangle \vert^2
= \alpha^2 \ const \ \vert \langle L \ 1s \vert \mathbf{r} \vert L \ np \rangle \vert^2 </math>
 
where <math>\psi^*</math> is the wavefunction of the unfilled orbital, '''r''' is the transition dipole operator, and <math>\alpha^2</math> is the "covalency" or ligand character in the orbital. Since <math>\psi^* = \sqrt{1-\alpha^2} \vert M_d \rangle - \alpha \vert L_{np} \rangle </math>, the above expression relating intensity and quantum transition operators can be simplified to use experimental values:
 
<math> D_0 = \frac{\alpha^2 h}{3n}I_s</math>
 
where n is the number of absorbing ligand atoms, h is the number of holes, and I<sub>s</sub> is the transition dipole integral which can be determined experimentally. Therefore, by measuring the intensity of pre-edges, it is possible to experimentally the determine the amount of ligand character in a molecular orbital.
 
==References==
<references/>
 
[[Category:Spectroscopy]]
[[Category:Synchrotron-related techniques]]
[[Category:X-rays]]

Revision as of 15:27, 17 October 2012

My name is Jestine (34 years old) and my hobbies are Origami and Microscopy.

Here is my web site; http://Www.hostgator1centcoupon.info/ (support.file1.com)

Ligand K-edge XAS is a spectroscopic technique that allows the direct study of metal-ligand bonding.[1] In a XAS experiment, electrons in ligand 1s orbitals are excited to unfilled p (principal quantum number n <= 4) and continuum states. This results in a large spectral feature known as a rising edge. Transitions at energies lower than the edge can occur, provided they are to orbitals with some ligand p character, and are called pre-edges. Such transitions are often observed in the data of complexes with metal-ligand bonding.

Pre-edge intensities (D0) are related to the amount of ligand (L) character in the unfilled orbital:

D0(L1sψ*)=const|L1s|r|ψ*|2=α2const|L1s|r|Lnp|2

where ψ* is the wavefunction of the unfilled orbital, r is the transition dipole operator, and α2 is the "covalency" or ligand character in the orbital. Since ψ*=1α2|Mdα|Lnp, the above expression relating intensity and quantum transition operators can be simplified to use experimental values:

D0=α2h3nIs

where n is the number of absorbing ligand atoms, h is the number of holes, and Is is the transition dipole integral which can be determined experimentally. Therefore, by measuring the intensity of pre-edges, it is possible to experimentally the determine the amount of ligand character in a molecular orbital.

References