XPS Info - Policies

This page describes the rules that are specific to our lab:

The maintenance of the XPS costs quite a bit of money and in order to 'earn' this money back, it has been agreed upon that using the XPS should be charged. The internal tariff consists of 2 parts: a fixed entry fee of € 25 and a variable fee of € 29,32 per hour for running the X-ray gun.

A project code needs to be provided while making a reservation. This project code will be charged for each reservation and the total time of X-ray use at the end of the month. The total time is derived from the MXR3 logfile, which is kept by the Avantage software.

If a single reservation was made for different projects, then the time of X-ray use, and hence the variable fee, will be split among those projects. If it is clear how much time is spent on the different projects, then this will be taken into account, if not, then the time will be split evenly. The fixed fee however will not be split but will be charged for each individual project.

2022 update: While full registration still takes place, no projects (of ChemE) will be charged...

Etching experiments can be done, but there are some rules and limitations.

Powder samples may never be etched. The reason is that aiming a beam of ionized argon (=etching) at your sample results in blowing your sample away. The blown away powder may end up in the analysis chamber and may potentialy hit the vacuum pump. The first will result in an ever deteriorating vacuum, whereas the second may even result into severe damage.

While your sample is being etched you must at least be present in the ChemE building. The reason is that the Avantage program sometimes crashes and leaves the guns on. So before you leave you check if the experiment is done and the guns are off.

It is assumed that anyone who works at any of the ChemE labs has done and passed the laboratory safety test. Access to a particular laboratory has to be granted by the laboratory supervisor.

Any XPS user can be given access to the XPS once he or she has shown to be able to work autonomously.

It takes about 5 minutes to pump down the loadlock from atmospheric pressure to about 5*10-6 mbar, at which the sample holder can be entered into the analysis chamber. However, a pressure of 5*10-6 mbar means there is still a huge pressure difference with the pressure inside the analysis chamber which is at about 5*10-9 mbar. That need not be a problem, but with powders and other high surface area samples it might be; it may take a long time to get the pressure back to reasonable values inside the analysis chamber once the sample holder has been entered. The reason is that the volatiles attached to the surface don't always come off easily.

Instead of using the ultra high vacuum side (analysis chamber) to remove the volatiles it is preferred to use the high vacuum side (loadlock).

It has been established that a pressure of 2*10-7 mbar (or less) can be reached in the loadlock and that this pressure can be reached overnight. Therefore our policy is that a sample can be placed in the loadlock at about 4 P.M. on the day before the actual measurement. On the following day, the day of the experiment, the sample holder can be entered into the analysis chamber from 8 A.M. onward.

When using the Vacuum Transfer Module (VTM) it is (kind of) mandatory to open the module within half an hour after closing it. Therefor instead of waiting for the vacuum to reach 2*10-7 mbar, before moving it to the analysis chamber, wait for the turbo pump of the load lock to come at speed and wait for another 10 minutes.

The sample preparation for measurements on nano particles is much like that of powder samples. In both cases material is put on either carbon or copper tape, where a visible amount means a measurable amount.

If you want to measure on nano particles samples, you will be requested to do the sample preparation on your own lab. The XPS lab is equiped with a decent fumehood that is suitable for powders, but that is not suited for working with nano particles.

Once your samples have been measured the waste can be treated as other powder samples.

The one glove policy for the XPS lab means that you wear one glove with which you can touch the sample holder and other parts, e.g. clips, that go into the XPS. Your other hand goes without glove and can be used to hold vials, scissors, tweezers etc.

The main purpose is to keep the XPS clean. So unlike the one glove policy in other labs: your hand is 'dirty' and the glove is clean.

Of course if you think safety requires you to wear two gloves, then you should do so. But if you wear two gloves, then it is assumed the second one is 'dirty'. Also if you wear two gloves, you will be asked to explain why you wear two gloves rather than one.

You shouldn't touch the mouse or keyboard of the PC with your glove, nor your mobile phone for that matter; your glove will become 'dirty'. The same applies if you wear a second glove; your glove will make whatever you touch 'dirty'.

Don't leave the lab wearing gloves.

A limited number of people will be given an account on the reservation website. Typically 2 or 3 persons per section.

Reservations can be made for any given day (on which the measurement will be done) assuming the samples will be loaded the day before. For each reservation both the name of the sample owner (not necessarily the one doing the measurements) and the BAANcode should be entered.

It is allowed to make reservations for a given Monday which would mean that the samples would be loaded on the preceeding Sunday. For samples that need extra time to get to adequate vacuum levels samples can be loaded the preceeding Friday or Saturday, in which case the reservation should start on Saturday or Sunday respectively.

With a sample holder that is 6x6 cm it looks like the maximum sample size would also be 6x6 cm. But because you need a clip to attach a sample to the sample holder and that clip has to fit into one of the holes of the sample holder, not all of the 6x6 area can be used. Furthermore the clip should be on the outside or between the sample and the edge of the sample holder.

With these restrictions the following sample sizes can be used:
5x6 cm; 1 sample with clips on either side
5x3 cm; 2 samples with clips on either side
2.5x3 cm; 4 samples with a clip on the outside

Training for autonomous use of the XPS can be given to a limited number of people, provided they will assist other non-trained members of their own group. This removes the sole responsability of the technician to assist untrained users and it spreads the knowledge.

Training will be given to small groups only, more specifically to 2 persons at a time. It is expected that these persons will stay part of their respective groups for a considerable time.

After the initial training session you will be monitored while doing XPS experiments until you are deemed capable of working autonomously.

When the XPS is being used, usually some waste will be generated.

Commonly the waste can be deposited in the appropriate garbage bin.

This is particularly true for any spill of powder samples and materials used to prepare the samples.

This is also true for used gloves that should also be deposited in the same garbage bin. Even if the gloves haven't touched any chemical, because there doesn't have to be a visible difference between clean and dirty gloves.

Powder samples are usually prepared on a carbon tape or on a copper tape attached to a small sample plate. These powder samples should be stored separately such that the sample plates can be recovered.

XPS info / ChemE / Delft University of Technology
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