Empty Glass Cells

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Figure 1.1  The GCV251 and GCV501 Empty Glass Cells feature a J. Young ^® Valve that can be closed to maintain a high-vacuum seal.

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Figure 1.4  These empty glass cells can also be mounted in our VC3C(/M) V-Clamp.

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View Imperial Product List

Item #	Qty	Description
GC251	1	Empty Glass Cell with Ø25 mm Fused Windows, 100 mm Long, One Fill Tube
VC3C	1	Large V-Clamp with PM4 Clamping Arm, 2.5" Long, Imperial
PM4	1	Large Adjustable Clamping Arm, 6-32 Threaded Post
GCH25R	2	Cap Heater for Ø25 mm Glass Cells, 10 W
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View Metric Product List

Item #	Qty	Description
GC251	1	Empty Glass Cell with Ø25 mm Fused Windows, 100 mm Long, One Fill Tube
VC3C/M	1	Large V-Clamp with PM4/M Clamping Arm, 63.5 mm Long, Metric
PM4/M	1	Large Adjustable Clamping Arm, M4 x 0.7 Threaded Post
GCH25R	2	Cap Heater for Ø25 mm Glass Cells, 10 W
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Figure 1.3  GC251 Glass Cell Shown

with Two GCH25R Heater Caps

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View Product List

Item #	Qty	Description
GC251	1	Empty Glass Cell with Ø25 mm Fused Windows, 100 mm Long, One Fill Tube
GCH25-75	1	Heater Assembly for Ø9, Ø19, or Ø25 mm x 75 mm Glass Cells, 15 W per Heating Element
ER4-P4	1	Cage Assembly Rod, 4" Long, Ø6 mm, 4 Pack
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Figure 1.5  Our Ø25 mm glass cells can be mounted in our GCH25-75 Heater using four ER4 cage rods.

Features

• Empty Glass Cells for Spectroscopy Applications
• 50 mm Long Glass Cell:
  • Both Ends Include Ø12.7 mm Windows
  • Available with One Tube for Filling
• 100 mm Long Glass Cells:
  • Both Ends Include Ø12.7 mm, Ø25 mm, or Ø50 mm Windows
  • Available with One Tube for Filling or Two Tubes for Flow
  • Single Fill Tube Cells Also Available with Genuine J. Young^®* Valve for Sealing
• 500 mm Long Glass Cell:
  • Both Ends Include Ø25 mm Windows
  • Available with One Tube for Filling
• Borosilicate Substrate for Cell and Windows
• High Transmission from 350 to 2200 nm
• Custom Design and Manufacturing Services Available (Contact Tech Support)
• Ø12.7 mm and Ø25 mm Cells are Compatible with a Variety of Heaters
• Glass Cells Also Available with GL-32 Threading for Interchangeable Windows

These empty borosilicate glass cells can be filled with vapors of specific atomic elements or molecular compounds, each of which has a well-defined absorption spectrum. Cells are available with either one or two fill tubes. A single fill tube is useful when sealing a cell while two fill tubes can be used to maintain constant gas flow. We also offer empty cells with a single fill tube and a J. Young^® Valve to seal the cell with a high-vacuum, greaseless stopcock (see Figure 1.1). Fill tubes with a 0.25" outer diameter are compatible with Ø1/4" compression fittings, and fill tubes with a 0.5" outer diameter are compatible with Ø1/2" compression fittings, as shown on the Vacuum Seal tab. As shown in Video 1.2, custom reference cells can be manufactured upon request, including different cell lengths, cell diameters, or fill tube configurations. Please contact Tech Support with inquiries.

Each cell is made from borosilicate glass, a rugged material known to resist chipping and cracking, and has high transmission from 350 nm to 2200 nm. The ends of each cell include Ø12.7 mm, Ø25 mm, or Ø50 mm fused windows. We also offer a variety of other empty cells for various spectroscopic applications as shown in Table 1.6. All glass cells on this page can hold a vacuum below 10^-7 Torr and withstand pressures up to 5 psi. The post-production cleaning process for these cells consists of an ultrasonic cleaning followed by a methanol rinse. The cell is then connected to a vacuum system and leak tested. The cells are not vacuum sealed when shipped; before using the cell in a vacuum setup, we advise users to follow a similar cleaning process for each cell.

These cells are commonly used in absorption spectroscopy; refer to the Application tab for a general overview of use with absorption spectroscopy. We also offer compact and Herriott multipass cells for gas absorption spectroscopy applications, as well as filled and sealed vapor and acetylene reference cells .

Mounting & Heating Options
The glass cells can be mounted in our V-Clamp Mounts, which are available in standard, kinematic, or Ø1.5" post-compatible versions. Please check that the cell diameter is supported by the mount. A pair of VBC1(/M) Post-Mountable Band Clamps can be used to mount a GC251L cell without marring. Our HT10K and TLK-H Resistive Foil Heaters can attach to the outside of glass cells with fused Ø12.7 mm or Ø25 mm windows via adhesive backing. Cells with fused Ø25 mm windows can be mounted in our GCH25-75 Glass Cell Heater as illustrated in Figure 1.5. This requires swapping out the included Ø6 mm cage rods with four ER4 4" long cage rods. We also offer the GCH25R Cap Heater for cells with fused Ø25 mm windows. This heater attaches directly to the end of a cell.

*J. Young^® is a registered trademark of GPE Scientific.

Table 1.6  Glass Cells Selection Guide
Empty Glass Cells with Borosilicate Windows	Glass Cells with Textured Antireflective Windows	Empty Glass Cells with Angled Windows	Empty Glass Cells with Brewster Windows	Threaded Empty Glass Cells	Vapor Reference Cells	Acetylene Reference Cells	Glass Cell Heaters

Absorption Spectroscopy

The reference substance pumped into the glass cell is associated with a unique absorption spectrum that serves as its fingerprint. The contents of a reference cell can be determined via a linear absorption measurement (as depicted in Figure 2.1). By scanning a tunable diode laser over a wavelength range and detecting light absorption with a photodetector, a series of peaks will be recorded, which is characteristic of the vapor inside the cell. Please note that we also offer pre-filled and sealed acetylene reference cells, as well as vapor reference cells with quartz or borosilicate substrates.

Figure 2.1  Absorption Spectroscopy Schematic

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Figure 3.1  Disassembled view of a KF25
flange-to-compression-fitting adapter.

Creating a Vacuum Seal with a KF Flange

Thorlabs' empty borosilicate cells can be used with our KF16 and KF25 Flanged Components and Accessories in order to manage gas flow in and out of the cell. Glass cells terminated with a Ø0.25" (Ø6.35 mm) fill tube can be inserted into a KF16C025 or KF25C025 Flange-to-Compression-Fitting Adapter, while glass cells terminated with one or two Ø0.50" (Ø12.7 mm) fill tubes can be inserted into a KF16C050 or KF25C050 flange-to-compression-fitting adapter.

To input the glass cell into a KF16 or KF25 vacuum system, follow the instructions below.

1. Select a KF16 or KF25 flange-to-compression-fitting adapter that is compatible with the fill tube diameter of the glass cell.
2. Coat a cleaned and inspected KF16CR-F or KF25CR-F Centering O-Ring in vacuum grease and place it on a base post or pipe.
3. Place the flange-to-compression-fitting adapter on top of the KF16CR-F or KF25CR-F Centering O-Ring and secure them with the KF16WNC or KF25WNC Wing Nut Clamp.
4. Loosen and remove the knurled locking knob, O-ring, and seal ring of the flange-to-compression-fitting adapter so its mating surface can be inspected and the included O-ring can be coated in vacuum grease. This will create a vacuum seal when the cell is inserted into the system.
5. Slide the open end of the glass cell tube through the top (side with the Thorlabs engraving) of the knurled locking knob, seal ring (with the counterbore seat for the O-ring facing the adapter body), and O-ring (in that order) of the flange-to-compression-fitting adapter.
6. Slide the glass tube into the flange adapter body and then slide the O-ring, seal ring, and knurled locking knob down the tube onto the flange adapter body. Tighten the knurled locking knob by hand.

It is not recommended to insert the glass tube into a fully assembled KF flange-to-compression-fitting adapter. The sharp edges of the glass tube may damage the O-ring, thus causing the seal to fail.