X-ray Diffraction Laboratory - Policies and Guidelines
Single Crystal Sample Analysis
The Single crystal data may be collected and analyzed
at the Facility in two ways.
- Through licensed users ('hands-on' operators of the Chemistry
Staff)
- By the Manager of the Service (for the non-users of the Chemistry
Staff) with the assistance of Ms. Geok Kheng Tan.
The use of SMART CCD System: The CCD will be used
by the licensed users and by the Manager on alternate weeks. The
week starts at 10 am on Mondays and the day starts at 10 am and
ends on the next morning at 10 am. The time slots of the users should
be booked a week in advance on the calendar posted in S7-04-10.
For given week any time-slot not reserved by 10 am on Monday may
be used by the users or Manager. If the user or the service cannot
use the CCD machine on a reserved time-slot due to any reason, he/she
must notify others as soon as possible. The main purpose is to utilize
the machine to the maximum. The weekend booking may be made from
10 am on Saturday until Monday 10 am.
Crystal Structure Determination
Service
Single crystal samples, which are to be analyzed
through the Service, should be checked with either one of the personnel
for appropriate size, shape and quality. Approved samples should
be properly labelled and left with a sample submission form duly
signed by their Research Supervisors in room S8-02-5A.
Sample Analysis--Scheduling
The X-ray instruments and computers are available
on a first-come, first-served basis. Exceptions are made on the
basis of sample instability, urgency of results, and concurrent
number of samples awaiting analysis from a particular research group.
Samples from NUS Chemistry research groups will be given utmost
priority from Monday to Friday. Samples from other (outside) groups
will generally be done on Saturdays and Sundays.
Special Sample Handling Requirements
Do not submit the crystals in containers that are
not easily accessible, e.g. a round bottomed flask. Submit the samples
in small cylindrical vials. Do all the single crystals look alike
in terms of color and morphology? Does your single crystal represent
the bulk of your sample?
Samples should be checked for sensitivities to
oxygen, water, light, temperature, etc., before being submitted
for analysis. Samples exhibiting one or more of these sensitivities
should be submitted in two or more properly sealed containers. Samples
sensitive to oxygen or water often remain more stable under a layer
of solvent. Please discuss samples requiring special handling with
the staff members to assure the best quality results.
Structural Databases
Cambridge Structural Database is available in
the near future free of charge to all members of the NUS Chemistry.
Publishing, Authorship and Acknowledgements
The following guidelines should be applied to
determine whether the person(s) who determine(s) a crystal structure
should be included as co-authors on manuscripts. Similar guidelines
are used by nearly all the other service facilities.
- If structural information is a major part of the intellectual
content of the paper, and if this information has been derived
primarily by X-Ray Crystallography that utilised the expertise
of the service, then the people involved should be considered
as co-authors of the paper. Most papers that include geometric
information from a crystal structure determined by the Manager
and his group members would be included in this category. The
people who performed the determination should assist in the
preparation of the manuscript. The names of the co-authors involved
in the determination and interpretation of X-ray data will be
provided by the Manager.
- If structural information is used only to confirm a result,
which is well established by other analytical means, then only
an acknowledgement for the assistance is necessary. In such
cases, the Manager and those involved would be allowed to publish
the structural results of the investigation independently, if
desired.
- Acknowledgements should be made for the technical assistance
if provided for data collection and reduction.
- Please include acknowledgements to the agencies that provided
funding to purchase the instruments and computers.
General Policies
All users of the X-ray instruments and computers
must comply with safety and legal requirements associated with these
X-Rays, X-ray instruments and computers. Specifically no user may
disable or modify any safety device associated with any X-ray instrument.
All users of the computers must abide any non-disclosure or related
agreement between NUS and any software vendors.
All lab policy decisions are made by the X-ray
Users of the Chemistry Department. All inquiries about policy matters
should be sent to the Manager.
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