Q A 2 XRAY Diffractometer.doc

Questions and Answers #2 Versatile Theta/Theta Xray Diffractometer

FA8224-12-R-0063

As of 05 June 2012, below are questions the Government has received and have given a response to. Whenever possible, questions are presented as originally asked. Otherwise, the question is presented to capture the main thrust or idea of the question or inquiry.

Q1: 3.8 – Line to Point Focus Conversion

There was some Q&A on changing from line to point focus. However, your requirement in 3.8 suggests a Polycapillary optic must be supplied for use with point focus. The Polycapillary is available from all vendors and is used to significantly boost the intensity for point focus applications significantly speeding up measurements for point focus methods. Please confirm a Polycapillary optic is a requirement for use with point focus methods.

A1: The system must be provided with a fast and easy method of switching between line and point focus. For this reason the system must include a Polycapillary focus conversion optic. Section 3.8 of the purchase specification has been revised.

Q2: 3.10 – Eulerian Cradle

The last sentence in 3.10 states the Eulerian cradle “Must allow full mapping of 50mm wafers”. In the Q&A, you stated, “The analysis only needs to be performed on a small portion of the large samples, not every point”. The Eulerian cradle provides Chi, Phi, and Z axes and the XYZ stage provides the XY mapping. To be clear, it would be helpful to remove this sentence from 3.10 to best understand the requirement. It is stated clearly in 3.11 XYZ Sample Stage.

A2: Yes, remove "Must allow full mapping of 50mm wafers" from section 3.10. Section 3.10 & 3.11 of the purchase specification has been revised.

Q3: 3.12 – Crystal Monochromator

There is still some confusion here. It appears you are really wanting a diffracted beam monochromator for use with both Bragg-Brentano (BB) and Parallel Beam (PB) methods based on the intended use and applications. The diffracted beam monochromator is used to suppress background from sample fluorescence, etc in a much superior way than electronic discrimination from a detector alone. The incident beam monochromator, such as Ge(220) is used to make high resolution thin film measurements on more perfect single crystal samples (not required for polycrystalline samples). Thus, we must ask for further clarification on the type - incident or diffracted beam? If diffracted beam, use with BB and PB modes as stated? If incident beam, must it be Ge220 2-bounce or Ge(220) 4-bounce incident beam monochromator?

A3: We require a single Dual purpose diffracted beam monochromator with the ability to be used with both Bragg-Brentano and Parallel Beam optics. The user shall be able to simply rotate the graphite crystal to change the crystal surface from curved for BB optics or to flat for PB optics or in the reverse. This procedure must be completed with simple rotation of the crystal with no need for realignment or removal of the monochromator from the X-ray diffractometer. Section 3.12 of the purchase specification has been revised.