Ex Situ Sample Measurements
MESQUIK is a MEasurement Service for QUIcK ex situ data collection obtained by routine analyses on a limited number of samples at the SuperXAS Beamline X10DA. Samples are sent to PSI and relative data are sent back by mail. We perform X-ray absorption spectroscopy measurements for all academic research communities (except for industrials). The beamline offers X-ray energies between 4.5 and 35 keV allowing for:
- The K edges can be obtained from Ti to I (Z 22-53)
- The L edges from I to Bi (Z 53 - 83)
A good tool to check the energy of different XAS edges can be found here: X-ray Absorption Edges (washington.edu). Check carefully if your samples present overlapping absorption edges (multiple metal ions in the sample) and that they can be measured in a sufficient energy range to provide the required information. You need to inform us about all elements presenting in the samples and their respective concentrations, to access the feasibility and measurement mode.
- The data collection modes possible are quick transmission (1-10 min acquisition time), quick total fluorescence yield with PIPS detector (1-10 min acquisition time) and step-scan partial fluorescence yield with a 5 element SDD detector (minimum 30 minute acquisition time) offered only on a very limited number of samples due to the long acquisition times.
Each request to MESQUIK is subject to a short (maximum 1 page) proposal submission with a quick internal review process. Our present aim is less than 12 weeks from proposal submission to delivery of data in your mailbox, if time is respected for deliveries of samples. For each proposal, a clear motivation for the study outlining the expected results and importance of the findings is expected. Additionally, a justification of the need for synchrotron radiation should be provided. In situ or operando experiments requiring a more complex setup and more time must submitted as standard proposal via the standard Call for Proposals (two deadlines per year). The call for MESQUIK proposals is continuously open. Proposals can only be considered if they are submitted electronically using the SLS Digital Users Office (DUO). After the acceptance of your proposal, the preparation of the samples is in your charge as well as the shipment to the MESQUIK service.
1) Proposal Submission
Proposal submission is managed through the DUO system: https://duo.psi.ch/duo/mesquik/superxas
The following guidelines should also be taken into consideration for the preparation of a proposal. (maximum length should not exceed 1 side of A4).
- Short Abstract
e.g. What is your overall project aim?
eg. What would you like to know about your material?
e.g. How have you gone about determining that XAS is the correct approach? Have you used other methods or techniques? Is there any complementary data available?
- Measurement requirements
e.g. Which XAS edges are required? transmission or fluorescence geometry? How many samples are to be measured? What are the data requirements, XANES or/and EXAFS?
- Summary of expected results
e.g. What will the results of these measurements provide for you and what are the next steps after this outcome?
In addition to these considerations on acceptance of the proposal the following guidelines should be followed.
2) Are your samples ready?
MESQUIK is a rapid measurement service for existing samples. Before preparing a rapid measurement proposal it is advised to contact the beamline staff to check the feasibility of the measurements. The list of samples to be measured should be complete. Additionally sent samples will not be measured.
3) Choice of experimental conditions and geometry
The edges to be measured should be clearly communicated for the samples. At present we only offer ex situ sample measurements and therefore no heating or cooling options are provided. It is expected that the samples will be shipped as prepared ready for measurements, therefore it is strongly advised to calculate which measurement method would be appropriate and how to then best prepare the samples for measurement. To calculate the expected edge step from a pressed pellet the XAFSmass software is very useful (XAFSmass — XAFSmassQt 1.4.0 documentation). For absorbance calculations in capillary geometry Compute X-ray Absorption (anl.gov) offers a versatile tool. Please contact the beamline staff if you have any questions regarding the correct preparation of your samples.
A pellet of greater than 5 mm in diameter should be used. A typical standard used at SuperXAS is a 13 mm pellet. Dilution of samples for pellet pressing should be undertaken with low absorbing materials such as cellulose or boron nitride. Careful grinding of the sample should be undertaken to assure a homogeneous mixture of the sample with the dilutant is achieved and that a well formed pellet is obtained. Additionally, sealing the pellets using kapton tape can help to avoid breaking the pellets during shipping or measurement.
Due to the minimum beam size at SuperXAS of 0.15 mm vertical focusing, and the typical beamsize used for ex situ samples of 1mm x 0.2 mm, the capillaries' diameter should be no smaller than 0.8 mm. Fused quartz glass capillaries or kapton tubes are ideal for measurements. Careful consideration of the capillary size and wall thickness should be taken to assure that sufficient data quality can be obtained at the desired absorption edge. The capillary has to be filled with the sample (ground powder typically) for a minimum length of 10 mm, homogenously well packed packed in the capillary tip (quartz wool can be used to affix the sample in the capillary tip for shipping) and then sealed (e.g. with a flame or glue); the end of the capillary must be straight.
4) Pack Samples
Each sample has to be packed individually and labelled properly with the name given in the DUO system. Although this might sound trivial, it is important you label correctly your samples. Please write the proposal number clearly on the package. Samples not correctly identified, will not be measured. We recommend packing carefully your parcel as we will not be responsible for any broken capillary during shipment which are subsequently not measured.
Users are responsible for shipping samples to SuperXAS beamline at SLS. All samples have to be sent or otherwise delivered in the same parcel to the following address:
Paul Scherrer Institut
5232 Villigen PSI
In the acceptance mail, you will be asked to confirm when the shipping has been made and you can provide a tracking number if necessary/available. This helps us warn you in case we have not received the parcel within a reasonable time.
5) Sample disposal
Samples will be disposed of 4 weeks after data collection. Under special circumstances, samples may be returned to you if arranged in advance with us. The payment for the return shipping should be arranged by users.
6) Publication of results
The MESQUIK service is possible thanks to Swiss federal contribution. By reporting publications that include SuperXAS, you demonstrate the value of this beamline to your research and help ensure the continuation of the service.