Inserting and Changing a Sample
Preparing the Sample
Depending on the nature of your sample, either fill the sample tube with a powder, or pipette a liquid sample into the sample tube. In either case, check out the resonator specific recommended sample height.
For liquid samples, make sure all liquid made it to the bottom of the sample tube. Avoid any air bubbles when filling the sample into the sample tube. For powdered samples, tap the bottom of the sample tube several times to make sure all powder is at the bottom of the probe.
Use adequate safety precautions when handling your sample, especially when handling toxic materials.
Assembling the Sample Holder
To get started, the sample tube needs to be mounted in the Sample Holder.
To mount the sample tube into the Sample Holder, follow these steps:
- Select the correct Collar size, Sample Holder Tip and Sample Holder Top size according to the sample tube OD
- Start with sliding the correct size teflon Collar over the sample tube. Make sure the Collar and the sample tube are oriented as shown in the figure above. The sample tube should slide in from the top to avoid damaging the Collar
- Insert the sample tube with the Collar into the Sample Holder Tip
- Slide the Spring over the sample tube. The orientation of the spring is not critical
- Slide the Sample Holder Top over the sample tube. The entire assembly should like the one shown in the figure above
- Begin screwing the Sample Holder Tip into the Sample Holder Top
- As you screw in the Sample Holder Tip into the Sample Holder Top, the spring will compress the teflon collet. Depending on the number of turns the spring is compressed more or less. Try not to overtighten the assembly. You should still be able to slide the sample tube through the Sample Holder assembly.
Do not overtighten the Sample Haolder Tip. The Sample Holder should have a firm grip on the sample tube. Overtightening the Sample Holder Tip could break the sample tube.
Recommended Sample Height
By adjusting how much the capillary is sticking out of the Sample Holder Tip the user can control how far the sample is inserted into the resonator. In general, Bridge12 requires that the distance between the center of the sample and the bottom of the Sample Holder Tip is about 1 inch (25.4 mm).
This is shown in the figure above (right side).
Removing the Sample from the Sample Holder
To remove a sample tube/capillary from the sample holder, slightly loosen the end cap and pull the capillary out from the bottom of the sample holder.
In general, it is not necessary to disassemble the Sample Holder unless a sample tube gets stuck or breaks and the Sample Holder needs to be cleaned
Inserting the Sample into the Probe
Once the sample tube is securely mounted on the sample stick, it can be inserted into the probe through the sample holder turret. The sample holder turret assembly includes a knurled nut, washer (ferrule) and an O-ring as shown in the figure below.
To insert the sample follow these steps:
- Stop the sample cooling (if running) and wait for the pressure in the cryostat to reach atmospheric pressure
- Loose the knurled knut of the turret (It is not required to completely unscrew the knurled nut)
- Remove the existing Sample Stick (or blind plug if present).
- Make sure to insert the Sample Stick all the way to the bottom of the resonator. The Sample Stick should rest on the bottom of the Sample Holder Tip. The Sample Stick has a mark at the top. This mark should line up approximately with the top of the knurled nut
- Under some circumstances, it may be easier to first assemble the sample stick with the knurled nut, the ferrule and the O-ring separately outside the resonator and load this assembly into the resonator. For this, additional spare parts are provided with the probe.
To remove the sample, reverse the above steps.
Do not force the sample stick into the probe (especially when operating at cryogenic temperatures). Forcing the sample stick into the resonator can potentially break the sample tube/capillary and case permanent damage to the probe.