Experimental determination totalreflection (X-Ray) [Archive]

Oliver Werzer

Mar14-05, 01:10 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Hello\n\nI do x-ray reflectivity measurements on organic films.\nTo measure the the curve is not a big deal, but to\ndetermine the total external reflection is difficult.\nFor a smooth surface and high scattering from the material\nthe edge is very \'sharp\'. But this is not the case for my\nmaterials. Therfore it is hard to find the exact value\nof the total external reflection. Is there a exact mathematical\nway to find the angle?\n\nbest regard\noliver\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Hello

I do x-ray reflectivity measurements on organic films.
To measure the the curve is not a big deal, but to
determine the total external reflection is difficult.
For a smooth surface and high scattering from the material
the edge is very 'sharp'. But this is not the case for my
materials. Therfore it is hard to find the exact value
of the total external reflection. Is there a exact mathematical
way to find the angle?

best regard
oliver

dbohara@mindspring.com

Mar15-05, 12:22 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nGet onto the LBL site for calculating x-ray refelctivity. You will\nneed to know the chemical formula for your film and its density. The\nprogram will give you reflectivity as a function of energy at a fixed\nangle or reflectivity as a function of angle for fixed energy.\nThe loss due to roughness is often approximated by the Debye Waller\nfactor R=R0exp(-(4*pi*sigma*sin (theta)/Lambda^2)^2\nwhere sigma is the rms roughness in angstroms, Ro is reflectivity for\nzero roughness, theta is the grazing angle, and lambda is the\nwavelength in angstroms.\nOliver Werzer wrote:\n> Hello\n>\n> I do x-ray reflectivity measurements on organic films.\n> To measure the the curve is not a big deal, but to\n> determine the total external reflection is difficult.\n> For a smooth surface and high scattering from the material\n> the edge is very \'sharp\'. But this is not the case for my\n> materials. Therfore it is hard to find the exact value\n> of the total external reflection. Is there a exact mathematical\n> way to find the angle?\n>\n> best regard\n> oliver\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Get onto the LBL site for calculating x-ray refelctivity. You will
need to know the chemical formula for your film and its density. The
program will give you reflectivity as a function of energy at a fixed
angle or reflectivity as a function of angle for fixed energy.
The loss due to roughness is often approximated by the Debye Waller
factor R=R0exp(-(4*\pi*\sigma*sin (\theta)/\Lambda^2)^2
where \sigma is the rms roughness in angstroms, Ro is reflectivity for
zero roughness, \theta is the grazing angle, and \lambda is the
wavelength in angstroms.
Oliver Werzer wrote:
> Hello
>
> I do x-ray reflectivity measurements on organic films.
> To measure the the curve is not a big deal, but to
> determine the total external reflection is difficult.
> For a smooth surface and high scattering from the material
> the edge is very 'sharp'. But this is not the case for my
> materials. Therfore it is hard to find the exact value
> of the total external reflection. Is there a exact mathematical
> way to find the angle?
>
> best regard
> oliver

Werzer Oliver

Mar18-05, 12:39 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>That\'s a problem.\nSometimes I do not have informations\non all components of the film. And also\nif you do temperature dependent experiments\nthe parameters are not known, since the change\nduring the experiment. Therefore I\nlook for a method to find the angle of total\nreflection experimentally. Then I can calculate\nthe other parameters.\n(e.g. cos(theta)=sqrt(2*delta),...)\n\nThe only thing I found\nis to look for the half of the intensity and mark this\nas the angle of totalreflection. But this is in my opinion\nnot enough.\n\nbest regars\noliver\n\ndbohara@mindspring.com wrote:\n> Get onto the LBL site for calculating x-ray refelctivity. You will\n> need to know the chemical formula for your film and its density. The\n> program will give you reflectivity as a function of energy at a fixed\n> angle or reflectivity as a function of angle for fixed energy.\n> The loss due to roughness is often approximated by the Debye Waller\n> factor R=R0exp(-(4*pi*sigma*sin (theta)/Lambda^2)^2\n> where sigma is the rms roughness in angstroms, Ro is reflectivity for\n> zero roughness, theta is the grazing angle, and lambda is the\n> wavelength in angstroms.\n> Oliver Werzer wrote:\n>\n>>Hello\n>>\n>>I do x-ray reflectivity measurements on organic films.\n>>To measure the the curve is not a big deal, but to\n>>determine the total external reflection is difficult.\n>>For a smooth surface and high scattering from the material\n>>the edge is very \'sharp\'. But this is not the case for my\n>>materials. Therfore it is hard to find the exact value\n>>of the total external reflection. Is there a exact mathematical\n>>way to find the angle?\n>>\n>>best regard\n>>oliver\n>\n>\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>That's a problem.
Sometimes I do not have informations
on all components of the film. And also
if you do temperature dependent experiments
the parameters are not known, since the change
during the experiment. Therefore I
look for a method to find the angle of total
reflection experimentally. Then I can calculate
the other parameters.
(e.g. cos(\theta)=\sqrt(2*\delta),...)

The only thing I found
is to look for the half of the intensity and mark this
as the angle of totalreflection. But this is in my opinion
not enough.

best regars
oliver

dbohara@mindspring.com wrote:
> Get onto the LBL site for calculating x-ray refelctivity. You will
> need to know the chemical formula for your film and its density. The
> program will give you reflectivity as a function of energy at a fixed
> angle or reflectivity as a function of angle for fixed energy.
> The loss due to roughness is often approximated by the Debye Waller
> factor R=R0exp(-(4*\pi*\sigma*sin (\theta)/\Lambda^2)^2
> where \sigma is the rms roughness in angstroms, Ro is reflectivity for
> zero roughness, \theta is the grazing angle, and \lambda is the
> wavelength in angstroms.
> Oliver Werzer wrote:
>
>>Hello
>>
>>I do x-ray reflectivity measurements on organic films.
>>To measure the the curve is not a big deal, but to
>>determine the total external reflection is difficult.
>>For a smooth surface and high scattering from the material
>>the edge is very 'sharp'. But this is not the case for my
>>materials. Therfore it is hard to find the exact value
>>of the total external reflection. Is there a exact mathematical
>>way to find the angle?
>>
>>best regard
>>oliver
>
>