X-Ray Fluorescence XRF by Astrik Gorghinian https://padlet.com/astrikgorghinian/XRF_en en-us 2016-01-08 15:55:23 UTC 2023-04-27 12:23:26 UTC hello@padlet.com https://padlet-uploads.storage.googleapis.com/88432459/09ec349efbfe687e675d37062db86e78d573d034/55b239ce60abfebb89d820fd9b0531ea.jpg About XRF astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88394733 XRF is a diagnostic technique widely used to perform elemental analysis (Z>13) present in a sample.

]]> 2016-01-08 16:01:55 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88394733 Typology of Investigation astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88396494

The sample needs not to be treated or prepared and the analysis does not alter it.

]]> 2016-01-08 16:09:06 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88396494 ND techniques -some examples astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88397041 -IR (infrared) reflectography
-radiography
-tomography
-gammagraphy
-holography
-ultrasound waveform analysis
]]> 2016-01-08 16:10:54 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88397041 X-Ray micro-fluorescence spectrometer astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88398947 2016-01-08 16:17:28 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88398947 astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88399990 http://w3.lnf.infn.it/

]]> 2016-01-08 16:21:02 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88399990 Measurement geometry astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88400281 2016-01-08 16:21:56 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88400281 astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88400526 Polycapillary optics: it is a beam focusing facility. Numerous (poly) hallow channels (capillars) are bent in such a way to capture and focalize X-Rays down to 50 micron spot.

]]> 2016-01-08 16:22:42 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88400526 Some techniques that employ X-Rays astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88807793 2016-01-12 08:19:30 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88807793 Physics Principles astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88810056 In case of photons, X-Ray constituents, the interacting processes that take place are absorption and coherent/incoherent scattering.
 
Absorption

The interactions that characterize absorption are: the photoelectric effect (interaction with the atom's electrons), pair creation (interaction with the electric fields of the surrounding charges), photonuclear reactions (interaction with nuclei), meson photo-production (interaction with mesons).

Scattering

The interactions that occur when X and gamma rays, with energies up to some MeV, strike a substance are:
  • coherent scattering from a free electron (Thomson)
  • coherent scattering from atomic electrons (Rayleigh)
  • incoherent scattering from atoms (Compton)

Compared to charged particles, photons are more penetrating (the interaction with matter is less probable). They might be removed from the primary beam, causing a decrease in beam intensity but not in beam energy.
]]> 2016-01-12 08:40:41 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88810056 XRF - the method astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88885724 When an X-Ray beam interacts with a specimen this emits characteristic X-Rays relative to the chemical elemental content.

The analysis of the acquired spectrum permits to identify the chemical elements present in the sample. It is capable of:

  • Qualitative analysis: chemical elements in the sample are identified.
  • Quantitative/semiquantitative analysis: provides the % weight concentration of the chemical elements present in the sample.
]]> 2016-01-12 15:09:07 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88885724 Experimental set-up astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88886007 X-Ray source (En<60 keV)

Sample

Detector Si(Pin)

Analog signal amplifier

Multichannel analyzer MCA (analog to digital converter)

Acquisition system/data processing

]]> 2016-01-12 15:09:58 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88886007 Application to Cultural Heritage artwork astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88892701 Paintings

Metal artwork

Stone artwork

Wooden artwork

Earthware and pottery

Glass and enamel

]]> 2016-01-12 15:28:18 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88892701 Nero astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88894110 Denarius 253568 Roma 66 DC

(Museo Archeologico Nazionale di Firenze)

http://www.archeotoscana.beniculturali.it/index.php?it/146/firenze-museo-archeologico-nazionale

]]> 2016-01-12 15:31:56 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88894110 Limits astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88896725 -it is a surface analysis

(depending on matrix composition the analyzed layer rang from few microns to some cm)

- chemical elements with Z<13 not detectable

- detection limits for each element are directly correlated to matrix composition, exciting energy and beam intensity

- energy resolution of the detector

]]> 2016-01-12 15:38:07 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88896725 XRF Spectrum astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/88903812 The XRF spectrum is a plot where on the x-axis the energy of the photons emitted by the sample is reported versus the counts (the number of photons emitted at a given energy) on the y-axis. The peak's position, respect to the energy, permits to identify the element present in the sample. The peak's area is directly correlated to the concentration % of the element in the examined specimen.

In the following figure, the XRF spectrum of a denarius issued by Nero (sample 253568) is reported.

]]> 2016-01-12 15:54:52 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/88903812 The measurement astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/89049872 Here is the operating device at INFN_LNF

]]> 2016-01-13 08:42:29 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/89049872 Index astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/89530749 -about XRF

-typology of investigation

-ND techniques: some examples

-some techniques that employ X-Rays

-physics principles

-photoelectric effect

-coeherent and incoherent scattering

-XRF - the method

-application to Cultural Heritage artwork

-experimental set-up

-polycapillary optics

-measurment geometry

-the measurment (video)

-XRF spectrum

-limits

-Bibliography

]]> 2016-01-15 10:44:16 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/89530749 Photoelectric effect and the X-Ray lines astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/89537541 2016-01-15 11:35:49 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/89537541 Scattering astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/89571151 2016-01-15 14:36:41 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/89571151 Bibliography astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/93148531 https://kaiserscience.wordpress.com/physics/electromagnetism/light-is-an-em-field/

https://courses.candelalearning.com/colphysics/chapter/29-3-photon-energies-and-the-electromagnetic-spectrum/

P. Craddok,  Science Investigation of  copies, fakes and forgeries, 2009 Elsevier 

]]> 2016-02-04 11:20:27 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/93148531 Play a game: Just mach spectra to materials astrikgorghinian https://padlet.com/astrikgorghinian/XRF_en/wish/97590908 http://LearningApps.org/watch?v=pct1wo5yt16]]> 2016-02-26 16:43:26 UTC https://padlet.com/astrikgorghinian/XRF_en/wish/97590908