Ravi Ananth

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Questions related from Ravi Ananth

What is the Rigaku software equivalent to Bruker LEPTOS?

I'm interested in software for simulating instrumental Bragg profile (strain free state), XRR profile and XRD Bragg profile to compare with experimentally obtained diffraction profiles for mono...

01 January 2018 8,654 2 View

What happens to RG contributions of a member upon his or her demise?

I was involved in this RG discussion and came up with this scenario: https://www.researchgate.net/post/Why_wustite_FeO_and_nitride_FeN_have_same_picks_in_GI_XRD?view=5a6ea20e5b4952dd7a765a23 One...

01 January 2018 9,621 33 View

How do I figure out the film thickness of the individual layer spatially from these diffractograms?

We've looked at an epitaxial film of GaN on a Si substrate using real time 2D Bragg XRD Microscopy (2D XRD rocking curve analysis). This specimen also had intermediate "buffer" layers of AlxGa1-xN...

11 November 2017 2,470 30 View

What is the likely Nanostructural origin for observations of the LiF (113)- XRD reflection rocking curve “integrated breadth squared” (β^2) map?

Real time XRD rocking curve data indicates a very interesting Nano structure in as-grown LiF crystal using the (113)- reflection ACT (asymmetric crystal topography). What Nanostructural features...

01 January 2017 7,771 1 View

What is the best method used to align the diffractometer plane/axis with respect to the incident beam direction?

Most of the XRD community is presently using 0D point counter or 1D linear PSD (position sensitive detector) in powder diffraction as well as rocking curve analyses. Any mention of the extinct...

12 December 2016 9,160 2 View

How do I calibrate the diffractometer 2Theta angles with this powder diffractogram of corundum standard from a Bruker D8 XRD instrument?

This data was acquired using the Onsight Technology AXIS (Advanced XRD Imaging System) 2D real time 27.5um pixel detector (25 mm diameter window) mounted on a Bruker D8 with Cu K Alpha, parabolic...

11 November 2016 5,991 5 View

Is this a reasonable way to convert experimental multi-dimensional XRD data of the reciprocal space into meaningful Nanostructural parameters?

Nano structural meaning to 3D XRD data: Converting the Bragg condition to crystallographic distortions and lattice strain fields topographically. The objective of any materials characterization...

11 November 2016 1,215 1 View

How do I compute b, Burgers Vector correctly using the Hirsch approach to computing dislocation density employing XRD rocking curve profile analysis?

Relative dislocation density using the approach of Hirsch et al. Dislocation Density, ρ = (β2)/(9.b2) b = Burgers Vector, andβ = Integrated Breadth (computed numerically from XRD profile data) Let...

09 September 2016 2,672 9 View

What depths can one typically probe with XRR, X-ray Reflectivity/Reflectometery?

XRR, X-ray Reflectivity or Reflectometry, is a NDE in situ method used to determine thin film dimensions and surface "flatness" for nearly a century now. What is the typical surface examination...

11 November 2015 10,175 15 View

Can XRR (X-Ray Reflectivity) be implemented in the Topographic Mode with spatial resolution over the sample surface? Is there value for such analyses?

Conventionally XRR, X-Ray Reflectivity, measurements have been conducted using a point or line source but always using the 0D point/scintillation/proportional type detector without spatial...

08 August 2015 8,461 2 View

Would anyone have a clue as to the origin of "unexpected spots" in the real time 2D XRR signal from thin film samples on substrates? Yoneda Spots?

X-ray reflectivity (XRR) is a technique abundantly used and vetted, for determining film thicknesses and "flatness" of thin film samples on substrates, over the past century. We have implemented...

07 July 2015 5,937 10 View

Does anyone know how to send out "hand shake" signals from the Bruker diffractometers to an external device through any communication port?

We are using a Bruker D8 diffractometer for XRD rocking curve analyses. We are interested in finding out the procedure for sending out Metadata parameters to an external device through any of the...

03 March 2015 6,703 3 View

Is it possible to precisely estimate the epitaxial film thickness with XRD rocking curve analysis? <2kW Power Sealed Tube Source!

We have super high resolution (76um Pixel,

11 November 2014 772 16 View

What is the conventional alignment procedure (critical for precision in XRD) for sample surface positioning collinear to the diffractometer axis?

i. How does one adjust for this type of sample displacement error (see figure in link below) with a conventional diffractometer measurement using the ubiquitous 0D Geiger counter (point...

11 November 2014 5,878 14 View

What is the best way to interpret REAL TIME 3D (X, Y, ω-2ϴ/ω/φ/χ) reciprocal space relative intensity data from HRXRD rocking curve analyses?

XRR, XRD Rocking Curve - (ω-2ϴ/ω/φ/χ)Omega-2Theta Scan, Omega Scan, Phi Scan & Chi Scan! NIST2000SRM - An important HRXRD (High Resolution XRD) Calibration Standard for symmetric and...

11 November 2014 8,500 37 View

Can you help regarding these transmission Laue 2D real time XRD images? Lysozyme!

We have acquired transmission Laue images from a Lysozyme crystal using a rotating anode at 5kW power. Point focus beam size about 200um or less. We have implemented some time tested image...

10 October 2014 7,884 3 View

Is the size measured a volume weighted size distribution? Is there an application for the Scherrer equation despite limitation with domain shape?

"My question is, if we use Rietveld refinement to get particle size, is the size measured a volume weighted size distribution or weighted by a different factor? Whatever the answer is, please...

10 October 2014 9,872 6 View

What is better for XRD rocking curve analyses 0D, 1D or 2D detectors? Why?

0D or the conventional Geiger counter type detectors have been in use since the Braggs. How does this match up against the more modern 1D & 2D detectors? Let us say I'm using a high resolution...

07 July 2014 5,075 13 View

What are the standard methods for determining powder particle size?

Would the accepted methods for determining particle size of Nano powders include the following? 1. TEM 2. SEM 3. STEM 4. XRD 5. Laser Scattering 6. Other

06 June 2014 6,306 44 View

Is it possible to determine the type & morphology of defects in single crystals by the shape of the Bragg XRD Rocking Curve Profile?

The X-ray Rocking Curve method has been perfected over the past half century to include the ability of examining homo-epitaxial and hetero-epitaxial structures. My interest would be in the...

02 February 2014 3,362 9 View

Is lower spatial resolution real time in situ XRD Microscopy a desirable precursor to more advanced methods like TEM, SEM, AFM etc.?

Bragg XRD Microscopy, a NDE tool that has been tried and tested for over a century was limited in spatial & temporal resolution by the detecting device. Presently the state-of-the-art in real time...

02 February 2014 3,395 12 View

Is it possible to quantify "texture co-efficient" for Aluminum foil 0.2mm (200um) thick using transmission Laue XRD Images?

Quantifying the "preferred orientation" in an Aluminum foil (0.2mm) sample using 2D diffractograms obtained with transmission Laue geometry: Figure 1. 2D & 1D diffractograms compared, Al...

01 January 2014 8,297 10 View

Is it possible to determine the epitaxial film thickness precisely using Bragg XRD Microscopy?

In order to use XRD to measure the epi film thickness precisely, several conditions must be met including and not limited to: 1. The sample must be assumed optically flat which is invariably the...

12 December 2013 4,583 10 View

What are the potential Nano structural reasons for the difference in the XRD Bragg profiles between substrate & epitaxial film?

Bragg profile is also known as RCP-Rocking Curve Profile or RSP-Reciprocal Space Profile. Let us examine this difference between the substrate (usually CZ grown) and an epitaxial structure grown...

12 December 2013 9,660 11 View

"Bloody Murder"! Why is there nearly such a visceral response to any disruption to "alignment" of existing diffractometers by XRD users & technicians?

1. Sensitivity of the XRD data on precise alignment. 2. Unwillingness to verify alignment prior to each measurement. Time prohibitive! 3. Unavailability of a real time tool to precisely "re-align"...

11 November 2013 4,864 31 View

What do you think?

"The intellect has little to do on the road to discovery. There comes a leap in consciousness, call it intuition or what you will, the solution comes to you and you don't know how or why." Albert...

10 October 2013 1,777 3 View

What are the possible Nano structural causes of asymmetry in the Bragg X-ray Rocking Curve Profiles for GaAs (CZ) & SiC (CVD) mono-crystal wafers?

Are there any publications concerning these topics? 1. Sub-grain/Mosaic Structure 2. Stacking Faults 3. Twinning 4. Dislocations 5. Other YouTube GaAs (004) Symmetric reflection (& more examples...

10 October 2013 5,022 10 View

What are the causes for ASYMMETRY in the Bragg X-ray Rocking Curve Profile (RCP) for a symmetric (004) GaAs reflection?

Real Time Bragg XRD Microscopy with GaAs symmetric (004) Bragg reflection: http://www.flickr.com/photos/85210325@N04/9430820747/ Is the asymmetry due to: 1. Theory 2. Stacking Faults 3. Twins 4....

08 August 2013 567 32 View

X-ray Rocking Curve Analysis of Super-lattice (SL) Epitaxial Structures: What are some of your practical experiences with this method?

I'm just reading this Caltech article and trying to decypher it. I surely could use some help understanding how to use peak position and intensity of the SL harmonic reflections to determine SL...

04 April 2013 622 29 View

Is this a reasonable way to eliminate effects of sample surface misalignment with the diffractometer axis? (Theta-2Theta Diffractograms)

Conventional XRD Pattern with a 0D point/scintillation detector/counter. We've used the diffraction pattern from the flat Aluminum holder as reference standard and shifted all the diffractograms...

03 March 2013 6,262 38 View

OAT - Oblique Angle Topography! Is this the first in the world? Do you know of anyone else in literature that has used this method for magnification?

Image magnification with XRD using oblique angle of incidence on the detector: A unique method is proposed, with experimental evidence to substantiate, for magnifying topographic images using XRD....

01 January 1970 7,409 5 View

What could the origin of "striations" be on a (113)- XRD reflection (integrated) topograph for the NIST 2000 SRM (standard reference material)?

I'm perplexed by the appearance of "striations" on this (113)- asymmetric reflection XRD topograph for the NIST 2000 sample. Both front and back! The topographs have been created by integrating...

01 January 1970 7,369 3 View

What methods are best suited for quantifying crystallographic micro lattice strain state?

What is the physical meaning of lattice micro strain and mean square micro strain? What is the difference between micro strain and mean square micro strain? A matter of scale or semantics?

01 January 1970 6,507 0 View