Services

 

The Characterization Laboratory "Ramón Gancedo" currently offers to external users as a service, also offered through the Service Catalogue of the CSIC, the following analysis:

 

  •  Mössbauer spectroscopy providing chemical information, structural and magnetic properties of iron atoms in powder samples in transmission mode, with the possibility of acquiring spectra at variable temperatures from ambient to 15 K.
  •  Mössbauer spectroscopy providing chemical information, structural and magnetic properties of iron atoms on surfaces and thin films, through the detection and measurement of electrons produced by internal conversion at room temperature.
  •  Chemical analysis of surface composition (the last 3 nm) by x-ray photoelectron spectroscopy of powder samples or samples surfaces, including determining the chemical state of the elements.

 

Other equipment is dedicated to scientific collaborations and research within the Group of Surface Analysis and Mössbauer Spectroscopy. It is recommended to contact the group for possible collaborations.

Available Equipment

  • A transmission Mössbauer Spectrometer with a closed-cycle helium cryostat (Air Products). Wissel transducer MVT-1000, with proportional counter LND-45431. Amplifiers and power supplies NIM from Canberra. Wissel multichannel CMAC 550.
  • A Mössbauer spectrometer for surfaces and thin films. Wissel transducer 1000. Parallel plate avalanche counter MVT using acetone as counting gas to detect electrons produced by internal conversion. Amplifiers and power suppliers NIM Canberra. Wissel multichannel CMAC 550.
  • 57Co and 119Sn radioactive sources (the laboratory is licensed by the CSN as a radioactive installation Class II).
  • Leybold LSH-10 XPS ultra-high vacuum chamber with Leybold dual anode Mg/Al X-ray gun. Vacuum Generators electron spectrometer with three electron multipliers, and data acquisition system based on a microcontroller. Leybold ion gun in-depth analysis. Rapid entry system and transfer bar. The system is based on CLAM2 VG with an energy resolution of 1.0 eV. The analysis chamber is at UHV (10-8 to 10-9 torr).
  • SPECS spectrometer (Phoibos-150 Analyzer) with an energy resolution of 0.9 eV, incorporated into a surface characterization system comprising electron diffraction, STM microscopy and low energy ion spectroscopy. Its analysis chamber reaches a vacuum of 10-10 torr.

 

Details: Mössbauer Spectroscopy

The available spectrometers and the technique are described here. The equipment offered to external users is the transmission spectrometer with cryostat, and the CEMS spectrometer.

The first spectrometer allows measurement of powder samples. The effective thickness of the absorbent iron should be about 5-10 mg/cm2 of natural iron. The minimum iron content is about 0.5 wt% for light matrices (for example, carbon, silicates). For other matrices must be greater than 5-10%. The measurement can be performed at room temperature or low temperature by a closed-loop cryostat that reaches 15ºK. Currently measures at room temperature or at 15 K are offered. At best, you can measure a sample per day at room temperature. Cooling to 15 K takes a day more. Typically counts are accumulated up to the point where the spectrum has a reasonable signal to noise ratio.

The second spectrometer (CEMS method) requires that samples should be somewhat conductive. Under favorable conditions layers of 5 nm can be analyzed, although the optimal is 50-200 nm layers (or bulk material surfaces). Samples should have a flat polished face of at least 1 cm in diameter, since the sample itself forms an electrode of an avalanche detector. There is an appreciable risk (20%) that discharges occur on the sample when applying a 1-1.5 kV voltage versus the other detector electrode. Such discharges typically deposit carbon on the surface of the sample (the counting gas is acetone).

Spectra were calibrated using the Fe-alpha spectrum. Within the service it is included a first set of spectra with an explanation of the information obtained.

 

Details: XPS

Restrictions on the size of the sample are given by the geometry of the specimen and sample introduction system. In the first system the size should be:

rectangular samples: 15 x 10 mm, 1mm thick maximum size

circular samples: 10 mm diameter, 1 mm thick maximum size

In the second system the sample size is less restricted and may have a size of a square of 2.54 cm thick with any dimension compatible with it (this spectrometer can measure small area XPS, 0.3 x 0.3 mm)

Samples must be able to withstand ultra-high vacuum (must be compacted solids or powders), and to avoid charge problems should be somewhat conductive. Samples are introduced by transfer bar accepting 1 cm x 2 cm samples. Powder samples can be mounted on adhesive carbon tape. In some cases X-ray irradiation may cause changes in the sample.

Usually spectra are calibrated using the energy of the carbon peak.

Typically two hours of pumping is required before starting the measurement. Depending on the number of spectra and the desired resolution, at least one day a sample is typically dedicated.

Within the service it is included a first set of spectra with the explanation of the information obtained.

 

Prices

Service Price
Mossbauer at room temperature 118.61€
Mössbauer at low temperature 152.73€
XPS 210,71€

The prices are only for external users. For more information please contact either This email address is being protected from spambots. You need JavaScript enabled to view it.or This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Level of implementation of quality systems

The laboratory employs systematic control of the offered characterizations and calibration methods. It also has documented procedures for the provision of service to customers for most of its activities. Therefore the laboratory is estimated to be classified as Level 3 quality within the REDLAB laboratories.