X-ray Diffractometer

AMENDMENT 2: The purpose of this Amendment is to provide Governemnt responses to vendor inquiries regarding the solicitation. Please see quesitons and responses below:

1. QUESTION: Cooling configuration (Specification 1.c)
The specification states that the X-ray tube source shall be cooled with an internal chiller and not require external water circulation. Would NIST consider an external closed-loop recirculating chiller, supplied as part of the complete system and requiring no facility water, provided it delivers equivalent cooling performance and system stability?

GOVERNMENT'S RESPONSE: Vendors are welcome to provide more than one quotation in response to the solicitation. All quotes will be evaluated in accordance with the requirements and evaluation criteria specified in the solicitation. Any alternative methods or solutions will be reviewed as part of the evaluation process to determine compliance with the applicable requirements. Please ensure that your proposal includes sufficient information and supporting documentation on how your approach meets or exceeds the stated specifications.

2. QUESTION: XRR absorbers (Specification 2.e)
The specification requires multiple absorbers, such as Cu films which can be stacked in 0.1 mm increments, for suppression of the direct beam during X-ray reflectivity measurements. Would NIST consider an equivalent configuration using selectable Cu absorbers of different thicknesses, provided the required attenuation range for XRR measurements is achieved?

GOVERNMENT'S RESPONSE: Vendors are welcome to provide more than one quotation in response to the solicitation. All quotes will be evaluated in accordance with the requirements and evaluation criteria specified in the solicitation. Any alternative methods or solutions will be reviewed as part of the evaluation process to determine compliance with the applicable requirements. Please ensure that your proposal includes sufficient information and supporting documentation on how your approach meets or exceeds the stated specifications.

3. QUESTION: Static stage for custom non-ambient cells (Specification 4.d)
The specification requests a static stage approximately 2 inches wide with screw holes for mounting custom non-ambient cells and states that the stage should be shaped as an L-bracket. Would a functionally equivalent, self-centering static mounting stage/adapter with appropriate provisions for securing custom non-ambient cells be acceptable if the mechanical design differs from an L-bracket?

GOVERNMENT'S RESPONSE: Vendors are welcome to provide more than one quotation in response to the solicitation. All quotes will be evaluated in accordance with the requirements and evaluation criteria specified in the solicitation. Any alternative methods or solutions will be reviewed as part of the evaluation process to determine compliance with the applicable requirements. Please ensure that your proposal includes sufficient information and supporting documentation on how your approach meets or exceeds the stated specifications.

4. QUESTION: Detector fluorescence rejection (Specification 3.a)
The specification requires detector energy resolution better than 400 eV at Cu Kα for fluorescence rejection. Our detector has an energy resolution of approximately 1800 eV but provides energy discrimination/filtering for fluorescence suppression. Would NIST consider this alternative detector approach, provided we can demonstrate effective fluorescence suppression for transition-metal-containing samples relevant to the intended applications?

GOVERNMENT'S RESPONSE: Vendors are welcome to provide more than one quotation in response to the solicitation. All quotes will be evaluated in accordance with the requirements and evaluation criteria specified in the solicitation. Any alternative methods or solutions will be reviewed as part of the evaluation process to determine compliance with the applicable requirements. Please ensure that your proposal includes sufficient information and supporting documentation on how your approach meets or exceeds the stated specifications.

Due date for quotations remains unchanged. All quotes are due no later than 9:00AM EST, on September 3, 2026.

END OF AMENDMENT 2.

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AMENDMENT 1: The purpose of this Amendment is to extend the quotation due date to 9:00AM EST, on September 3, 2026. 

END OF AMENDMENT 1.

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See attached FORM SF1449.