From Miguel Gregorkiewitz
From [email protected] Fri Jun 15 16:25:49 2001
Date: Fri, 15 Jun 2001 17:28:28 +0200
Subject: Re: STX: Suppliers of "no screen" film for Crystallographic X-ray work???
To: Lachlan Cranswick
Dear Lachlan,
Some time ago, we compared 3 brands of photographic film
materials suitable for powder diffraction cameras (Gandolfi etc):
Kodak Direct Exposure, CEA Verken Reflex, and AGFA Structurix
D7. The first two were quite similar in grain size and Ag/m^2, and
CEA also offered 1-side coated material (code# -15 instead of -25).
Agfa Structurix D7 was much finer in grain size and slower (by a
factor 5 or so), but had the highest resolution. A pity that it comes
on blue base which was not as nice for scanner readings. There is
now another emulsion too, Structurix D8, which seems more grainy
and rapid, but we didn't test it yet.
As far as we know, Agfa is continuing production, Kodak was
available until a few months ago here in Italy, but for CEA Verken
there may be problems. I'll let you know.
If you are looking for alternative Ag-photographic emulsions, we
were quite happy with Kodak MINR and Kodak NMB which were one-side
coated fluorescence screen containing mammography films, a bit
expensive but acceptable speed and resolution. X-OMAT seems a
popular brand among resellers and hospitals, but was terribly foggy
with high background, we never understood why. Also not very sensitive
(~1g Ag/m^2).
For some reading try:
S Abrahamsson et al, J Appl Cryst (1981) 14:256-260.
WC Phillips & GN Phillips, ibid (1985) 18:3-7.
There was also a IUCr comparison of about 20 different emulsions
in commerce during the 70 or 80ies, I can find a copy in my
archives if you like.
Anyway, we have probably all to think about IPs, or learn to make
our own gels soon!
Best
Miguel
Miguel Gregorkiewitz
Dip Scienze Terra, Universit�
via Laterina 8, I-53100 Siena, Europe
fon +39'0577'233810 fax 233938
e-mail [email protected]
From Miguel Gregorkiewitz
From: [email protected]
Date: Tue, 26 Jun 2001 08:57:24 +0200
Subject: film material
To: [email protected]
dear Lachlan,
the bad news is that CEAverken indeed has closed its production
of photographic material.
Agfa is continuing with Structurix D7 and D8, the latter being faster
by a factor of 1.7 at the cost of lower resolution, but they couldn't
specify me at what level, I think resolution may be sufficient for
most X-ray crystallographic work. Unfortunately, however, D8
comes only in ugly formats like 30*40 cm2 or larger.
best
Miguel
Miguel Gregorkiewitz
Dip Scienze Terra, Universit�
via Laterina 8, I-53100 Siena, Europe
fon +39'0577'233810 fax 233938
e-mail [email protected]
From Miguel Gregorkiewitz
From: [email protected]
Date: Wed, 27 Jun 2001 18:41:46 +0200
Subject: references
To: [email protected]
Hi Lachlan,
here go the missing references. #1 and #2 are to Nguyen's program
for Debye-Scherrer film digitalization, #3 to my paper on the
interpretation of Gandolfi patterns regarding the missing reflections,
and #4 to the IUCr report on about 20 different film materials:
JH Nguyen, R Jeanloz. A computer program to analyze x-ray
diffraction films. Rev Sci Instrum (1993) 64:3456-3461.
B O'Neill, JH Nguyen, R Jeanloz. Rapid computer analysis of X-ray
diffraction films. Amer Mineral (1993) 78:1332-1335.
M Gregorkiewitz. Geometrical limits and improvement of the
diffraction optics in Gandolfi cameras. J Appl Cryst (1994) 27:855-
859.
SC Dawson, M Elder, OS Mills (on behalf of the Commission on
Crystallographic Apparatus of Int Union Crystallogr). A survey of X-
ray film characteristics. ~1986
As far as I know, Nguyens program is the only code which
accounts for azimuthal alignment and ellipse fitting, although
something in this direction has also been done at ESRF (Pulford et
al, ESRF Report 1994/5, p.79).
*************
The IUCr report has probably never been published, so I just send
you a copy of this and all the staff I put together some years ago
when I was interested in an optimized Gandolfi attachment. You
will also find a brochure referring to such attachment as realized by
a small manufacturer in Spain, the device works quite well but I
don't know if they are still interested to fabricate it.
Cheers
Miguel
Miguel Gregorkiewitz
Dip Scienze Terra, Universit�
via Laterina 8, I-53100 Siena, Europe
fon +39'0577'233810 fax 233938
e-mail [email protected]