开云体育

I asked before with no response but since you are now down at Ca, it seems appropriate to check again. Does anyone want a small sample of sodium metal, sealed under argon in glass. Sounds fancy but it is (they are) just low pressure sodium vapor lamps pulled from working fixtures. When cooled, the sodium vapor condenses to a small lump at the tip of the bulb (they normally run upside down). (I have the sockets and the 120VAC ballasts as well) Randall

A nice tutorial link on the subject: http://xrf.guru/Concepts/FilterAndVoltage/index.html and another from Bruker, the XRF gun folks: http://www.xrf.guru/WorkshopVI/TracerDocumentation/Manuals/files/TN1001%20Filter-Voltage-Current%20Selection.pdf essentially saying the same things, the first probably written by a tech the second by a sales person. From the first link this is what I needed to know, condensed down: To see an element, you must send in at least 2 keV more of energy to see that element. Source Filter: Allows you to focus on key elemental ranges to identify elements at detection limits The green filter is composed of 150 μm (6mil) Cu, 25 μm (1mil) Ti, and 300 μm (12mil) Al. The green filter sees the optimization in a higher energy range, from 13 - 17 keV (Th, Rb, U, Sr, Y, Zr, Nb, Mo). Use 40kVp @30uA The red filter uses 25 μm(1mil) Cu, 25 μm (1mil) Ti, and 300 μm (12mil) Al - with the red filter we end up with a zone of about 9 - 12 keV were there is an ideal signal to background ratio for elements (Pb, Hg As, Br, Au). Use 40kVp @30uA The black filter (250 μm Cu/25 μm Ti/300 μm Al). You can see much higher peaks for the heaviest elements (Ba, La, ?Ce). Use 40kVp @30uA or 45kVp @30ua for K’s from La+Ce The above are the K-Edge type filters, utilizing the abrupt change in X-Ray absorption at the K (or L) edge of an element. Each element is different. These are effective and don/t require much in the area of exciter power. FYI what I'm doing with Cd and Al etc. metals is different and requires more power (or longer count times). The Cd for example is more of a secondary-target system with a built in attenuator. I like to think of it simply as a wavelength shifter. Both obviously work, in different ways. Geo

Dud, I used the thickness you recommended. " you would use 150 um Cu , 25 um Ti, and a 300 um Al filter" Super thin stuff. The AL is an alloy, it should be pure. Will work on that more tomorrow. These are shop-made, not the real ones which cost a fortune (hundreds$$) and are NIST certified etc. https://ludlums.com/images/product_manuals/L-430%20&%20431%20&%20434.pdf Geo

You called it a source filter. It works by K-edge? sFrom: "DFEMER" <dfemer@...> To: [email protected] Sent: Tuesday, October 27, 2020 3:40:29 PM Subject: Re: FW: [XRF] 59.5keV spectrum cleanup Geo, We know you know what you’re doing but none of us know what you were doing. Please also be descriptive in what we’re looking at. Pretty pictures don’t do much without context. Write the experiment up What the objective, what filter, where, with what metal, what thickness, what target, what source, count times? What’s an edge filter? Dud

It has been rumored that Crayola (of crayons fame) has a new brilliant blue crayon called bluetiful. What is its elemental composition is the question. The first to submit an MCA file documenting such will receive an “atta boy” pat on the back and full bragging rights. Dud

Free software for quantitative xrf analysis Compatible with Dppmca Amptek software.The software opens Dppmca file. Only problem it is not first order calibration So I cannot proceed beyond a certain step. Only manage to do a rough peak search Maybe some of you are familiar and can provide some assistance Thanks Taray

PART-1 Definitions. Some are specific to the XRF sub-discipline. Practicing XRF is what we do and discuss on this chat board. For those who are reading but aren't practicing XRF techniques yet, lets lay out some of the theory behind XRF- First the initials stand for X-Ray Fluorescence. A few definitions of the noun fluorescence in layman is "shine" another is "glow".. For our our purposes the definition of General Science is a little more detailed: The giving off of light by a substance when it is exposed to electromagnetic radiation, such as visible light or x-rays. As long as electromagnetic radiation continues to bombard the substance, electrons in the fluorescent material become excited but return very quickly to lower energy, giving off light, always of the same frequency. Fluorescent dyes are often used in microscopic imaging, where different dyes can penetrate and illuminate different parts of the sample being examined, helping to distinguish its structures. Compare phosphorescence The light produced in this way So in very basic terms, the "F" in XRF is to shine by means of energy transfer at an atomic level, and the XR part defines the "light" we detect as being X-Rays. To make the atom fluoresce X-Rays can be done by a number of means, not always having to do with applying X-Rays to the sample. The external energy can come from an electromagnetic source of from charged particles like Alpha Particles and fast electrons. A lot of the XRF we look at are excited by the energy ejected from the nucleus of a newly created element a result of radioactive decay of its parent element. This latter X-Ray and Gamma Ray from the daughter is usually immediate, but can be delayed, sometime much longer. Such daughter elements are appended with the small letter "m" for metastable. Check out Cs-137/Ba-137m decay scheme. Ba-137m has a half-life (T/2) of 2.55 minutes. Remember radio waves, microwaves, infrared, visible light, ultraviolet light, X-Rays and Gamm Rays are all "light"- simply electromagnetic radiation of different energy levels.. In this practice we consider X-Rays as being electromagnetic energy being formed from the electron shell of an individual atom, while Gamma Rays originate within an atom's nucleus. Things will be a simpler in the long run if we all consider "Radioactive Decay" the process that changes parent element to a different element# by changing the proton# in an atoms nucleus. Beta and Alpha decay are the most common, but there are many others. Once the element has changed to it's new nucleus, there are secondary emissions from that element's nucleus- these include the Gamma Rays and the production of XRF from the daughter product's electron shells. A very obvious example is the major radioactive check disc we use for calibrating XRF systems: Fe-55. It decays by Electron-Capture (EC) to Mn-55. If we apply an external energy to stable Fe, we get back the XRF energy of Iron Ka1= 6.40 keV (there are others too). If we turn off the external exciter and test radioactive Fe-55, on our instruments, we see X-Rays of the daughter which is 5.90keV. There's no mistaking the two with a Si-PIN or other high resolution detector. Highlight- natural X-Rays from radioactive element are of the daughter, induced X-Rays of stable elements is of that element. Important! Keep the above in mind as we discuss XRF. Let's stop here for discussion, we can add more definitions later via the edit function. Geo