Sample Holders attach to the tip of Rotary
Drives and provide rotation to the sample and connection for sample
services such as heating or cooling. Several types of sample holder are
available, offering a range of movements and sample position. Features,
such as low magnetic permeability and small swept volume allow these
products to be used with sensitive surface science applications.
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| Features |
- Wide choice of positive and accurate rotational movement options.
- The sample is normally attached to one of the service accessories
which fits to the backplate of the sample holder. These accessories
include heaters or plain sample mounts. The sample size is normally
14mm x 14mm with an option for 25mm x 25mm.
- All sample holders can accept the 'HST' resistive heater, the
'EBH' electron bombardment heater or the 'SPA' sample mounts. Extra
thermocouples can be provided.
- All sample holders accept the 'LN' liquid nitrogen cooling
accessory, and are compatible with the Helistat and Cryoax cryostats
for liquid helium cooling.
- The very low sweep volume of these sample holders allows samples
to be positioned very close to the analysis equipment.
- Most sample holders have low magnetic properties for use with
sensitive surface science applications.
- The SH series have shielded isolators to reduce electrostatic
charging.
- Offset adjustment enables the sample surface to be preset with
respect to the primary or tilt axis. This allows for different
sample thickness and is important where the sample must be
coincident with the axis of rotation.
- Sample Holders are normally supplied as part of a manipulator
configuration, but they can be supplied individually for mounting to
Rotary Drive shafts.
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| Construction |
| Sample Holders are fully UHV compatible.
The main materials used are stainless steel, alumina, beryllium copper
and OFHC copper. The construction of each sample holder varies to give
the required axis of rotation. However, the method of attachment and
actuation of the secondary motion is the same in all cases. |
| Terminology |
R1 rotation. Referred to as primary
axis or polar axis rotation. This rotation about the Z-axis.
R2 rotation. Referred to as azimuthal rotation, where
axis of rotation is normal to sample service.
R3 rotation. Referred to as sample tilt or flip,
where the axis of rotation is parallel to the sample service. |
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| Sample Offset. This is the
distance of the sample holder backplate from the R1 axis. Offset
adjustment is available on all models. |
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H dimension. This is the distance
from the rotary drive tip to the sample centre. Increasing this
dimension allows larger samples to be fitted and the rotational range
increased.
Swept Radius. This gives the clearance required around the
primary axis to avoid clashes when the primary axis is rotated around
360°. |
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Sample size and placement. All
sample holders are intended for use with a service accessory such as the
HST heater. These are equipped with clips suitable for retaining samples
up to 1.6mm thick and 14mm square. The clips are also suitable for
wobble stick transfer. For thicker and larger samples alternative clips
and services can be provided.
Temperature Ranges. Specifications refer to the achievable
temperature of a heated (or cooled) sample plate when no sample is
attached. The sample temperature is dependant on the nature of the
sample itself and on experimental conditions.
Enclosed wiring. The unique VG Scienta design that allows
the electrical connections to pass through the azimuthal spindle.
Combined with the 'Cryo-joint' (another unique VG Scienta
feature to control the cooling braid, whilst actually improving
performance) the service connections are efficient, tidy and
electrostatically screened. |
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| Magnetic properties. Low
magnetic induction is important in low energy spectroscopy and is
determined by the relative permeability of the material and by the
magnetic field strength. the residual induction is measured at the
sample centre after the application of a strong magnetic field. |
