Am 20:59, schrieb James Holton:
...
The loss of the 1/r^2 term arises because diffraction from a crystal is
compressed into very sharp peaks. That is, as the crystal gets larger,
the interference fringes (spots) get smaller, but the total number of
scattered photons must remain constant. The
Actually, people forget the 1/r term because it is gone by the end of
Chapter 6 of Woolfson.
Yes, it is true that, for the single reference electron the scattered
intensity falls off with the inverse square law of distance (r) and,
hence, the amplitude falls off with 1/r. However, the units
Hi Bernhard,
On Wed, Oct 13, 2010 at 08:07:04PM -0700, Bernhard Rupp wrote:
[...]
BR
PS: Just in case it might come up - there is NO destructive interference
between F000 and direct beam - the required coherence that leads to
extinction/summation of 'partial waves' is limited to a single
PM
Please respond to
William Scott wgsc...@chemistry.ucsc.edu
To
CCP4BB@JISCMAIL.AC.UK
cc
Subject
[ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F in this picture isn't
@JISCMAIL.AC.UK
cc
Subject
[ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F in this picture isn't required to be vertical (purely
imaginary)?
http://www.doe
@JISCMAIL.AC.UK
cc
Subject
[ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F in this picture isn't required to be vertical (purely
imaginary)?
http
On Thu, 2010-10-14 at 08:41 +0200, Tim Gruene wrote:
This sounds as though you are saying that a single photon interacts
with several
electrons to give rise to a reflection.
Not only with several - it shouldn't be much of an exaggeration to say
that the photon senses all the electrons in the
, October 13, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced together an answer to the question I
wanted to ask, which hopefully is right
...@uoxray.uoregon.edu
To: CCP4BB@JISCMAIL.AC.UK
Sent: Thursday, October 14, 2010 11:28 AM
Subject: Re: [ccp4bb] embarrassingly simple MAD phasing question (another)
Just to throw a monkey wrench in here (and not really relevant to
the original question)...
I've understood that, just as the real part
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD
phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced together an answer to the
question I
wanted to ask, which hopefully is right.
On Oct 13, 2010, at 1:14 PM
To:CCP4BB@JISCMAIL.AC.UK
Sent: Wednesday, October 13, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD
phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced together an answer to the
question I
On Oct 14, 2010, at 7:40 AM, Ed Pozharski wrote:
On Thu, 2010-10-14 at 08:41 +0200, Tim Gruene wrote:
This sounds as though you are saying that a single photon interacts
with several
electrons to give rise to a reflection.
Not only with several - it shouldn't be much of an exaggeration to
] embarrassingly simple MAD
phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced together an answer to the
question I
wanted to ask, which hopefully is right.
On Oct 13, 2010, at 1:14 PM, SHEPARD William
...@chemistry.ucsc.edu
To:CCP4BB@JISCMAIL.AC.UK
Sent: Wednesday, October 13, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD
phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced
On 10-10-14 01:34 PM, Ethan Merritt wrote:
...
The contribution from normal scattering, f0, is strong at low resolution
but becomes weaker as the scattering angle increases.
The contribution from anomalous scattering, f' + f", is constant at
all scattering angles.
...
My
On Thursday, October 14, 2010 01:18:04 pm Bart Hazes wrote:
On 10-10-14 01:34 PM, Ethan Merritt wrote:
...
The contribution from normal scattering, f0, is strong at low resolution
but becomes weaker as the scattering angle increases.
The contribution from anomalous scattering, f'
I have always found this angle independence difficult. Why, if the anomalous
scattering is truly angle-independent, don't we just put the detector at 90 or
180deg and solve the HA substructure by Patterson or direct methods using the
pure anomalous scattering intensities? Or why don't we see
Good evening citizens and non-citizens,
On Thu, Oct 14, 2010 at 08:21:19AM -0700, William G. Scott wrote:
On Oct 14, 2010, at 7:40 AM, Ed Pozharski wrote:
On Thu, 2010-10-14 at 08:41 +0200, Tim Gruene wrote:
This sounds as though you are saying that a single photon interacts
with several
On Thu, Oct 14, 2010 at 04:28:26PM -0500, Jacob Keller wrote:
I have always found this angle independence difficult. Why, if the anomalous
scattering is truly angle-independent, don't we just put the detector at 90
or 180deg and solve the HA substructure by Patterson or direct methods using
On Thu, 2010-10-14 at 23:31 +0200, Tim Gruene wrote:
you observe that each photon decides on exactly one slit
that it goes through.
That is if you observe which slit it goes through.
--
I'd jump in myself, if I weren't so good at whistling.
Julian, King of
On Thursday, October 14, 2010 02:28:26 pm Jacob Keller wrote:
I have always found this angle independence difficult. Why, if the anomalous
scattering is truly angle-independent, don't we just put the detector at 90
or 180deg and solve the HA substructure by Patterson or direct methods using
On Oct 14, 2010, at 2:31 PM, Tim Gruene wrote:
I would like to understand how the notion of a photon being scattered from all
electrons in the crystal lattice explains the observation that radiation
damage
is localised to the size of the beam so that we can move the crystal along and
shoot
On Oct 14, 2010, at 2:28 PM, Jacob Keller wrote:
I have always found this angle independence difficult. Why, if the anomalous
scattering is truly angle-independent, don't we just put the detector at 90
or 180deg and solve the HA substructure by Patterson or direct methods using
the pure
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F in this picture isn't required to be vertical (purely
imaginary)?
http://www.doe-mbi.ucla.edu/~sawaya/tutorials/Phasing/phase.gif
(Similarly in the Harker diagram of the intersection of
...@jiscmail.ac.uk] On Behalf Of
William Scott
Sent: Wednesday, October 13, 2010 10:48 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F in this picture isn't
Hi Bill,
the picture does not show Fa (as a vector), but the vector addition Fp+Fa+iFa
(it might be a naming convention of the picture to write Fa instead of iFa,
but that's a matter of taste really).
Furthermore Fa has the same phase as Fa plus the contribution of i, which
corresponds
to the
The Fa vector is always a 90 degree left turn from the Fa vector. For a
centrosymmetric heavy atom substructure such as 1 mercury site in P21,
the Fa vector would point straight up or down.
hope that helps,
Citizen Dan
William Scott wrote:
Hi Citizens:
Try not to laugh.
I have an
!)?
Jacob
- Original Message -
From: William Scott wgsc...@chemistry.ucsc.edu
To: CCP4BB@JISCMAIL.AC.UK
Sent: Wednesday, October 13, 2010 12:48 PM
Subject: [ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing
respond to
William Scott wgsc...@chemistry.ucsc.edu
To
CCP4BB@JISCMAIL.AC.UK
cc
Subject
[ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F in this picture isn't required to be vertical
Thanks for the overwhelming response. I think I probably didn't phrase the
question quite right, but I pieced together an answer to the question I wanted
to ask, which hopefully is right.
On Oct 13, 2010, at 1:14 PM, SHEPARD William wrote:
It is very simple, the structure factor for the
Dear Bill,
The discussion is becoming complicated because of the mixing of notations.
There is a theory or model which describes the atomic scattering factor as
f = f0 + f' +if
from which the structure factor is calculated. That right angle that you see in
the picture you sent us with that
Bill,
If I understand you correctly, the problem turns to be understanding
coordinate system.
The coordinate system in the plot in your original email is not a
complex one but a polar coordinate system [|F| and phase (polar
angle)]. In order to add the contribution of an atom with
Message -
From: William Scott wgsc...@chemistry.ucsc.edu
To: CCP4BB@JISCMAIL.AC.UK
Sent: Wednesday, October 13, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD phasing
question
Thanks for the overwhelming response. I think I probably didn't phrase the
question quite
On Oct 13, 2010, at 4:21 PM, Jacob Keller wrote:
While we are on embarrassingly simple questions, I have wondered for a long
time what is the reference phase for reflections? I.e. a given phase of say
45deg is 45deg relative to what? Is it the centrosymmetric phases? Or a
theoretical wave
PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD phasing
question
Thanks for the overwhelming response. I think I probably didn't phrase the
question quite right, but I pieced together an answer to the question I
wanted to ask, which hopefully is right.
On Oct 13, 2010
, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced together an answer to the
question I
wanted to ask, which hopefully is right.
On Oct 13
On Oct 13, 2010, at 3:09 PM, Tim Gruene wrote:
Dear Bill,
The discussion is becoming complicated because of the mixing of notations.
There is a theory or model which describes the atomic scattering factor as
f = f0 + f' +if
from which the structure factor is calculated. That right angle
, detectable but not measurable.
Lijun
Jacob Keller
- Original Message -
From: William Scott wgsc...@chemistry.ucsc.edu
To: CCP4BB@JISCMAIL.AC.UK
Sent: Wednesday, October 13, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD phasing
question
Thanks
Does f000 mean the direct beam? Having a hard time imagining such a miller
index or the corresponding planes...
No, F000 is NOT the direct beam. I may not have made that clear enough in
some of my drawings and captions, and it will be emphasized in the second
printing/ebook. There is in fact
] Summary : [ccp4bb] embarrassingly simple MAD
phasing
question
Thanks for the overwhelming response. I think I probably didn't
phrase the
question quite right, but I pieced together an answer to the
question I
wanted to ask, which hopefully is right.
On Oct 13, 2010, at 1:14 PM, SHEPARD
...@chemistry.ucsc.edu
To:CCP4BB@JISCMAIL.AC.UK
Sent: Wednesday, October 13, 2010 3:58 PM
Subject: [ccp4bb] Summary : [ccp4bb] embarrassingly simple MAD phasing
question
Thanks for the overwhelming response. I think I probably didn't phrase the
question quite right, but I pieced together an answer
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