XRF

This post is about X Ray Fluorescence Spectroscopy. If the Name sounds too complicating or sounds uninteresting feel free to ignore this post. Stephen Hawking says in the preface to his book-"The Universe in a Nutshell", that his publisher advised him saying that the inclusion of an equation or technical details will cut down his readership by half. So he didn't do it. But I'm going to write about X Ray Fluorescence Spectroscopy in this blog, and I don't care about the readership. Besides, at the moment I'm writing this post, I don't have any readers! I 'm writing this as a way of remembering what I learned in preparing a presentation on XRF under the module Analytical Methods.
Back to the topic. When high energy electromagnetic radiation-usually in the form of X Rays, strikes a material, The atoms in the material may get ionized. If the energy is sufficient, an atom can lose an electron from one of its lower orbitals. This causes an instability in the atom and therefore an electron from a higher orbital fills in the gap created by the dismissed electron. This causes a release of energy again in the form of X rays but with lower energy than the primary, incident X rays. These secondary X rays are called Fluorescent X rays, and the phenomenon is named Fluorescence.
This released energy corresponds to the energy difference between the orbitals involved and is unique to the atoms of a particular element. This makes it possible, to identify the elements present in a sample by analyzing its fluorescent X rays. In fact, analyzing here means measuring the energy of the emitted radiation. This method of analysis is called X Ray Fluorescence Spectroscopy.
The XRF Spectrometer consists of the primary X ray Source, the sample, the detector and the computer. XRF Spectrometers are further classified into two types;
1. Energy Dispersive Spectrometers(EDS/EDX)
2. Wavelength Dispersive Spectrometers(WDS/WDX)
In the energy Dispersive type the fluorescent X rays are directly measured and is the faster and cheaper method. The Wavelength dispersive type uses an analyzer crystal to separate the different wavelengths before they are focused into the detector. This method the more sensitive method.
A variety of elements can be identified using XRF Spectroscopy and it is commonly used in Geo Chemical investigations and mineral analysis. Recent developments to this technique and emergence of handheld XRF Spectrometers has brought about its application in fields like forensics and archaeology as well. XRF Spectroscopy was recently used to analyze the painting techniques used by Leonardo Da Vinci in creating his world famous masterpiece-"Mona Lisa".

The Onion Earth

I knew the internal structure of the Earth and its layers- crust, mantle, outer core, and inner core since I was 9 years old. I also knew about plate tectonics and how continents change over time. But few days ago when I was thinking about the plate movements and volcanoes I came across a contradiction... If the crust lies on top of the mantle and if the upper part of the mantle is solid, how do the plates move about? where does the lava come from?
After reading about it I saw that I had not known the existence of a layer within the mantle until then..-The "Asthenosphere". Upon further reading I found that there are so many layers of the earth in addition to the above mentioned primary layers.. like an Onion.
So the Earths tectonic plates comprise of the crust and the uppermost, solid part of the mantle. This is called the "Lithosphere" below the lithosphere lies the asthenosphere which is also part of the mantle. The asthenosphere is of higher temperature and partly molten. It on this layer that the lithospheric plates lie and slowly move giving rise to the continental drift. Beneath the mantle lies the usual liquid outer core and the inner core.

Image taken from Wikipedia

 The onion like structure of the earth even extends beyond the surface of the earth into the atmosphere. The layers of the atmosphere starting from the bottommost layer are, Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.

Remembering Pi..

3.14159265358979..... Pi is arguably the most famous constant in mathematics. First introduced in primary school geometry, it continuously appears even in the most advanced areas of mathematics and physics. The digits of Pi are still being calculated and no pattern has been found in the occurrence of the digits.
In the past memorizing the digits of Pi has been an obsession, although today memorizing Pi would be of no use because any pocket calculator would give its value up to the 8th decimal place..Nevertheless I feel it is good to remember this important constant to at least its 6th decimal place (because we are capable of  memorizing several 10digit phone numbers! ). However, the purpose of this post is to give a an easy way of remembering the digits of Pi, which I found in a book that I read. It would be useful for those who don't want to memorize numbers..Use the sentence "How I wish I could recollect Pi" in which the number of letters in each word equals a digit, to remember Pi up to 6 decimal places. To remember up to 10 decimal places, use, "How I wish I could recollect Pi easily using one trick ". I found the above sentences in the book "Strength in Numbers" by Sherman K. Stein.

Asperger's Syndrome

 I recently read an article about Asperger's syndrome in the Sunday Times and was surprised to find that among the ones who suffered from it were people like Isaac Newton, Albert Einstein, Abraham Lincoln, Beethoven, Marilyn Monroe, Virginia Woolf and even Elvis Presley! Among the notable people affected by this syndrome in the present are Tom Hanks, Robin Williams and Bill Gates. Clearly this is a very interesting.. It seems that Aspergers Syndrome somehow helps a person to achieve brilliance in his/her field.

The article went on to say that Asperger's Syndrome is not a disease, but a "set of behavioural traits". It had also listed some of the traits that can be identified in children as follows,

• Reluctance to look at the face of the other person when having a conversation.
• Not discussing what happens in school with the parents.
• Abhorrence of a change in routine – if it happens, throwing huge tantrums.
• In-depth study and focus on a subject he likes and speaking avidly on it.
• Cannot comprehend jokes. If someone jokes with him he will misunderstand it and think ill of the other person and walk off.
• Acting and talking in a mature manner, not in keeping with his age.
• Preference for the company of older people than his peers.
• Unresponsive to others’ feelings.
• Living in a world of his own.
• Preference for solitude.
• Having unusual ideas and views which result in others teasing him. As others don’t agree with his views, huge friction occurs. He will also try to impose his will on others, against the wishes of the majority and fight tooth and nail which will cause rows both in the classroom and the playground.
• He will lose his temper frequently and be unable to control it along with being intolerant of others’ view.
• He will be very selective of the food he eats or the clothes he wears, rejecting all else except his preferences.
• He will be fearful of unusual things.
• Intolerant of delay, he will want everything done immediately.
• He has only a chosen few he calls friends.

 -Extracted from The Sunday Times Mediscene May 15 2011-

In my opinion, many of us have at least some of these traits..It is a part of what makes us unique as individuals. Try imagining a person without any of these traits. It would be a person with no specific ideas or preferences, with no ability to focus his attention on something and with low self esteem... So it seems that it is better to have Asperger's syndrome rather than being a workaday person without it  ;)

The "Face" on Mars

In 1976 when the spacecraft Viking1 was orbiting the planet Mars taking photographs of its surface, one photograph caught the attention of many. It showed a formation on the surface of the planet looking strikingly like a human face.

                              (Image from:Wikipedia, the free encyclopedia)
Astronomers at NASA immediately wrote it off saying it was an illusion created by lighting, however upon further examination it was found that the actual 3 dimensional structure itself resembles a human face; i.e its not merely an illusion.

This "face" created a lot of excitement during that time and theories that include extra terrestrial intelligence or lost alien civilizations were put forward to explain it.

Although a slight air of mystery still surrounds this face of mars, It is now widely accepted that the "face" is a natural formation. It seems very rare and highly improbable but, such natural formations have occurred on earth too.  The old man of the mountain, the Badlands Guardian are two such examples.

In my opinion the face of Mars has something to do with our perception too. We see a face because we expect to see a face, and because our brains are very good at identifying faces. Many ancient cultures have seen a face, a rabbit, or something else on the moon. Our ancestors saw so many images and patterns among the stars. Our minds always look for patterns in things and succeed in finding them. It has been proven mathematically that any large collection of objects has patterns concealed in it, therefore it follows that we can identify patterns in practically anything. It is because of this that we associate a face or something else with natural formations and heavenly objects.

"It is likely that our very existence as a species owes much to this ability to delineate patterns. Evolution may have made us a little too adept at spotting them. Our propensity to see patterns where none exists at all is witnessed by ancient Man's enthusiastic identification of ploughs and hunters, crabs and scales tracing out patterns of stars we call the constellations, or by modern Man's enthusiasm for Martian Canals." 
- The World Within the World-John D. Barrow (Oxford,1990)   

Sri Lanka's loss at the CWC Final

Thousands of hopes were shattered when Sri Lanka lost the final match of the ICC Cricket world Cup for the second consecutive time. However more than the loss, it was the poor quality of cricket played, and the lack of enthusiasm shown by some of the players in the team that disturbed many viewers.

To begin with, the changes and replacements made in the playing squad just for the final match were surprising..Why make drastic changes to a team that has already performed very well? also, leaving out the bowler with the best record for the team in the tournament, and bringing in cricketers who haven't played a single match in tournament to play the final was puzzling.

Changes and replacements kept aside, the performance in the field was also of very poor standards. Dropping important catches and misfieldings were increasingly common. There was a sharp contrast between the Indian and the Sri Lankan teams in terms of fielding.. While the Indians were diving across the ground to save runs, Some of our fielders just lazily bent over while the ball went passing them.

However only some of the players lacked the enthusiasm. Some others showed great commitment and sportsmanship specially when batting. This was a match we could have won. This is why the ardent fans of Sri Lanka Cricket are upset... Anyway what's done is done and hopefully our cricketers will learn from the mistakes made this time and gear up for winning the next world cup.

Sky Observation at the Arthur C. Clarke Institute

After the first semester examination in our University, We were supposed to study 3 non technical modules-two of  which were compulsory and one of our own choice. The module I chose was Astronomy. The reasons for my choice were the interest I had in Astronomy, The interesting course contents and most importantly, The observation sessions.

We had two observation sessions at the Arthur C. Clarke Institute. One in the night for the observation of the Moon and the Planets and one session in the morning for observation of the Sun.
The telescope at the Arthur C. Clarke Institute, is the largest telescope in Sri Lanka. It is a Cassegrain Reflector type telescope and has a primary mirror of diameter 45cm. It uses an Equatorial Mount and is moved using computer controlled servo motors. It uses CCD cameras as the main imaging device.

It was unfortunate that the on the night we had our moon observation, the sky was very cloudy and not a single star could be seen. Also it was lightning. Because of this we couldn't use the Cassegrain reflector that night. Instead we used a much smaller reflector to look at the moon. The image of the moon was not clear due to the obstructing clouds.

The following day was better. We viewed the sun through the filtered Cassegrain telescope and saw two Sunspots. We also saw the Chromosphere of the Sun through an H-alpha filter.

The two sessions at the institute were very interesting and educational. It was a truly memorable experience.