PP3010 Cryo-SEM/Cryo-FIB/SEM Preparation System

Mounting, freezing and transferring specimens – easy with the Prepdek^® workstation

Freezing and specimen handling and workflow

The PP3010 Prepdek^® workstation is fitted with a slushy nitrogen freezing station, connected to the pumping system. Rapid freezing reduces ice crystal damage and results in improved specimen preservation. For handling pre-frozen material the Prepdek^® freezing system allows specimens that have been frozen by alternative freezing methods (or stored field specimens) to be manipulated – in or just above liquid nitrogen – and then transferred under vacuum into the PP3010 preparation chamber for subsequent processing and observation.

Additionally, the 25314 TEM Prep Slusher and 25852 glove box interface/airlock options allow workflow amongst a range of other platforms, including cryo-TEM, cryoultramicrome, XPS and glove box. Please see below for details.

Cryo transfer device – including vacuum storage

The vacuum transfer device is compact (fits easily into one hand), reliably vacuum-tight and has a bayonet connection to the specimen shuttle to ensure rapid pick up and transfer.

Set into the Prepdek^® work surface is a pumped storage tube for the cryo transfer device (see Prepdek^®  workstation section below).

Specimen stubs, shuttles

The PP3010 is supplied with universal 10 mm specimen stubs with surface slots, holes and a flat area – useful for most specimen types. Blank and slotted stubs are also included. In addition, a range of optional holders is available, including shuttles for large specimens and top-loading holders for high-pressure freezing, TEM Autogrids^TM (for cryo-FIB/SEM applications) and clamping shuttles for hard specimens.

You can view examples of these in the Additional Information section, or download a PDF from this link: PP3010 holders.

Cryo preparation chamber

The cryo preparation chamber is connected directly to the microscope and includes a highly efficient nitrogen gas cold stage, extensive cold trapping and facilities to fracture, sublimate and sputter coat specimens. The chamber is fitted with two fully integrated and interlocked gate valves. The outer load-lock valve includes a pumped airlock which accepts the cryo transfer device – the inner SEM valve ensures rapid high-vacuum to high-vacuum specimen exchange.

Highly efficient gas cooled stage and cold traps

At the heart of the cryo preparation chamber is a nitrogen gas cooled specimen stage. The stage has a dovetail fitting to accept a cryo shuttle and can be precisely controlled over a temperature range from 100^oC to -190^oC. Large gas cooled cold traps located above, below and behind the specimen stage ensure clean, high vacuum conditions in the chamber.

Both the cold stage and cold traps are cooled with the fully integrated CHE3010 off-column cooling system (see below), which at normal operating temperatures give typical hold times of at up to 24 hours between fills (provided the nitrogen gas is dry).

High visibility

The aQuilo^® chamber has superb chamber visibility. In addition to the large front window (75 x 150mm) there are two top viewing ports and the chamber is lit by three LEDs.

An optional stereo microscope can also be fitted to the cryo preparation chamber

Cold fracturing

Twin fracturing tools manipulators (actively cooled) are available and allow a range of specimen types to be cold fractured.

The PP3010 is fitted as standard with a front-mounted fracturing and manipulation device. The ball-jointed mount offers the flexible movement of the blade which can be used both as a surface pick (probe) and a fracturing knife.

An optional micrometer-advanced fracturing tool with a rigid blade is available in addition to the standard front-mounted tool.

Fractured fragments are captured in the large cold trap located below the specimen stage.

Automatic sublimation and sputtering

Sublimation temperatures and times can be preset and stored for easy retrieval. The process is fully automatic and graphically displayed on the control screen, showing the actual versus the predicted temperature curves.

The high-resolution sputter coater is an in-house design, being based on the market-leading Quorum “Q Plus” series of benchtop coaters. The coating system will give fine-grain films essential for FE-SEM applications. A platinum target is fitted as standard – optional metals include gold, gold/palladium, chromium and iridium. An optional fully integrated carbon fibre evaporation head (11920) can also be fitted.

An optional terminating film thickness monitor is available (12147).

Turbomolecular pumping – high vacuum performance

The preparation chamber is pumped by a remotely-positioned 70 L/s turbomolecular pumping system. Typical preparation chamber vacuums when cold are in the region of 10^-7mbar. Positioning the turbomolecular pump away from the SEM ensures total elimination of mechanical vibration and has the advantage of significantly reducing the total cryo system mass connected to the SEM. A vacuum buffer tank (remotely located in the Prepdek^®) is automatically pumped when required. The pumping system is connected to the preparation chamber by flexible stainless-steel bellows, which allows flexible positioning of the pumping system.

A 5 m³/hr  rotary vacuum pump (13034) is required to “back” the turbomolecular pump and for slushing and rough pumping operations. The rotary pump can be located up to five metres from the system, allowing remote location if required. Dry pumping alternatives are available – see Ordering Information.

Prepdek^® workstation

The Prepdek^® workstation has been designed to allow specimen mounting, freezing (plus pre-frozen specimen manipulation) and transfer device storage on one ergonomically designed work surface. The control electronics are mounted in a sealed but accessible cabinet beneath the Prepdek^®.

Set into the work surface is a pumped storage tube that allows the cryo transfer device to be stored under vacuum conditions when not in use.

Panel PC touch screen user interface

The PP3010 is controlled using a large touch screen panel PC, mounted on the Prepdek^® workstation. User-defined ‘recipes’ can be entered and stored for instant future access. The screen can be set to suit operator preferences; for example, vacuum measurement can be displayed in millibar, Pascal or Torr.

Many of the key steps in the specimen preparation process are automated (system set up, gas flow control, sublimation and sputter coating). Further help is available through a series of on-screen videos.

SEM cold stage, cold trap and cooling system

A highly stable, thermally isolated, nitrogen gas-cooled stage attaches to the SEM stage. The SEM stage and cold trap are cooled by separate cold gas circuits – both capable of reaching temperatures of -190°C or lower. This configuration allows the operator to select stage and cold trap temperatures that are optimised for specific specimens. For example, for some non-biological materials, it is useful to hold the specimen at very low temperatures – for example, a cold stage temperature of -175°C. This is possible with the PP3010 as cold trap temperatures of -190°C or lower can be selected – but not possible with conduction-cooled systems.
The SEM cold stage has a temperature range of down to -190°C and temperature stability of < 0.5°C.

Compatibility with SEM stage bias mode

The PP3010 cold stage is fully compatible with SEM stage bias/beam deceleration modes of up to 5kV.

CHE3010 off-column cooling

The CHE3010 is a fully integrated, remotely mounted cooling system that comes as standard with every PP3010. The CHE3010 is used to cool the SEM stage, SEM cold trap and cryo preparation chamber cold stage and cold traps and will typically reach temperatures down to -190°C.

The CHE3010 is remotely positioned (typically on the floor behind the microscope) and at normal operating temperatures can run for up to 24 hours between fills. This greatly simplifies the cryo process (no more checking on dewar status and topping up) and allows overnight, unattended operation – particularly useful for some automated FIB/SEM “slice and view” protocols.

Single port interface to the SEM or FIB/SEM

Where SEM geometry allows, both the cryo preparation chamber and the SEM cooling system can be fitted to a single chamber port (the minimum port diameter is 38 mm). This gives a tidy installation and frees up a valuable chamber port.

Options and accessories

Specimen shuttles and stubs
The PP3010 is supplied with a selection of holders and a range of additional specimen shuttles and stubs is also available. (See Ordering Information for details).

Carbon evaporation and film thickness monitor
A carbon evaporation attachment (20996) and a terminating film thickness monitor (12147) can be fitted. Both are fully integrated (no external control boxes required).

Pressurised LN₂ dewar

The PP7450/60L is a highly recommended option that generates dry nitrogen gas used for cooling the SEM cold stage & cold trap and cryo preparation chamber and cold shields. In addition, LN₂ can be decanted for slushing (freezing). During normal operation (8 hour/day, preset conditions on auto flow control), the PP7450/60L will generate dry nitrogen gas for up to three days usage.

If the PP7450/60L is not included then appropriate, locally sourced, nitrogen gas cylinders can be used. It is important to ensure that it has low moisture content – if in doubt please contact Quorum.

Cryo workflow options

Glove box valve/airlock interface (25852) – for vacuum or inert gas transfer

The airlock is connected to a glove box using a generic NW fitting and for most applications requires a suitable pumping system (13034 rotary pump or 2336 turbomolecular plus diaphragm pumping system).

The airlock is designed to accept the PP3010 vacuum transfer device.

For full details of this and other accessories please see Ordering Information.

TEM Prep Slusher option (25314)

Offers an easy and convenient way of transporting pre-frozen specimens to and from the PP3010

• Conveniently locates into the Prepdek workstation of the PP3010
• Freely transportable, e.g. between high pressure freezer, cryoultramicrotome and the PP3010
• Ideal for loading/unloading TEM grids and grid holders
• Tilting holder for cryo shuttles (holders). Allows the easy transfer of specimens from external freezers (e.g. high pressure, jet, slam etc)
• Option for PP3010 and previous PP3000T and PP2000/PP2000T models.