2 Minute ReadHappy Halloween! Since Halloween is fast approaching 👻 I thought I would publish this seasonal post on the strange and eery properties of the Horse Chestnut tree that anyone can try. To see what I mean, take a look at this short video… https://www.youtube.com/embed/bw3cqeBmha4?feature=share So what is going on here? This strange fluorescent emanation is […]
Spooky Horse Chestnut Fluorescence! Read More »
6 Minute ReadIntroduction One of the very first posts on this site introduced the basics of Absorption Spectroscopy and the concepts of Absorbance and Transmittance of light through homogeneous materials. In this article we are going to consider this topic in a little more detail through the Beer-Lambert law and use the relationship to determine the concentration
The Beer-Lambert Law and Spectrophotometric Analysis Read More »
6 Minute ReadIntroduction In two earlier posts on this site we recorded the absorption spectrum of molecular iodine I2 with some simple instrumentation. The first section outlined the basic theory giving rise to the vibrational absorption bands in the spectrum of any diatomic molecule. The second section described how the home experimenter can produce an absorption spectrum
The Fluorescence Spectrum of Iodine Read More »
4 Minute ReadIntroduction In part 1 we covered the construction of the SAM III boards, the connections between the boards and incorporated the boards into a suitable box. In this post we move on to the three fluxgate sensors themselves. We explain how these have to orientated and positioned relative to one another in order to send
The SAM III Magnetometer – Part 2 Read More »
6 Minute ReadIntroduction In several previous posts the physical principles describing the fluxgate magnetometer were introduced. We went on to construct a simple magnetometer based on a single fluxgate sensor, available from FG sensors in Slovenia. This was installed in a small thermos flask to provide some reasonable means of keeping the temperature fairly constant and data from
The SAM III Magnetometer – Part 1 Read More »
5 Minute ReadIntroduction Spectrum tubes are a very useful way to introduce science students to the study of the interaction of light photons with matter and the subjext of optical spectroscopy. They are often seen in demonstrations in high schools and early university lab classes to teach the basic principles of quantum theory and atomic and molecular
5 Minute ReadUploading the Data to a Website If you have been following so far, at this point we should have the Raspberry Pi set up, configured, and the necessary program modules installed. This final post describes how to upload the data to a website or server. The simplest way to do this is to create a shell
Aurora Monitor – Part 4 Read More »
11 Minute ReadIntroduction Well, it has taken me a few months to get around to finishing this particular project, but here are the final sections that I have split into two parts. In the Part 1 and Part 2 articles, we covered the basics of the fluxgate magnetometer (FGM). We explained how it can be used to
Aurora Monitor – Part 3 Read More »
10 Minute ReadIntroduction This post describes three simple demonstration spectrometers that the home experimenter can set up, with a minimum of optical elements, in order to get involved with examining spectra. These optical design demos are able to capture and record the spectrum of any light source. Whether it is a neon lamp, with its characteristic red
Three Simple “Demo” Spectrometers Read More »
8 Minute ReadIntroduction A thin film can be defined as any material with a thickness ranging from a fraction of a nanometre (nm) to a few microns (μm). The manufacture of thin films onto various substrates is vital to high-tech industries. The deposition of optical coatings, the production of highly integrated chips on silicon wafers, the manufacture
How Thin is a Thin Film? Introduction to Thin Film Reflectometry Read More »
3 Minute ReadThis post will be fairly short since I’m away from the “home lab” and relaxing in Thailand. I’m staying at a place called The Sanctuary on Phangan Island (Koh Pha-ngan), which I guess comes as close to paradise as one can get. I was here before a few years ago at The Sanctuary’s Wellness Centre
A Quick Blog Post from Paradise Read More »
4 Minute ReadIntroduction Many spectral line profiles reported elsewhere on this blog frequently take advantage of a very versatile software package called Spectragryph. The software was developed as a successor to an earlier version for managing and processing spectral data called Spekwin32. Both apps were the creation of Dr. Friedrich Menges who, since 2016, works full time
6 Minute ReadIntroduction Here is the emission spectrum of hydrogen gas in a discharge tube recorded at moderate spectral resolution: Fig. 1 The Spectrum of Hydrogen Gas in a Discharge Tube It was obtained, as with many other emission spectra on this blog, by using either a mini Tesla coil (widely available online) or a high voltage
The Hydrogen (and Deuterium) Emission Spectrum Read More »
6 Minute ReadIntroduction Mention the words “chemistry set” to anyone who grew up in the 1950’s and 60’s, and watch their reaction. If they had an interest in science as a child, it is likely that their eyes could well glaze over as they fondly remember their first chemistry set and recount the experiments and fun they
Chemistry Sets of Today and Yesterday Read More »
5 Minute ReadIntroduction This is the second part of a project to build an Arduino-controlled constant temperature enclosure. In the first part of the project we set up the Arduino microcontroller to receive temperature and humidity data from a sensor and then to send this data to a type 1602 liquid crystal display. In this post we
Arduino-Controlled Temperature Enclosure – Part 2 Read More »
4 Minute ReadIntroduction In previous posts the fluxgate magnetometer was described. The frequency pulses from the fluxgate sensor were captured by an Arduino microcontroller then sent to a Raspberry Pi for further analysis and display. One drawback with fluxgates is that they are also temperature dependent. One way to minimise temperature variations is to bury the sensor
Arduino-Controlled Temperature Enclosure – Part 1 Read More »
6 Minute ReadIntroduction In Part 1 of this 4-part post, the fluxgate magnetometer (FGM) was introduced. We outlined how this device can be used to detect changes in the Earth’s geomagnetic field caused by the solar wind. These changes can predict, to some extent, the amount of solar activity and the chances of you seeing an aurora
Homemade Aurora Monitor – Part 2 Read More »
6 Minute ReadIntroduction Magnetometers are instruments used to measure magnetic fields. They have been around in different forms since the great physicist and mathematician Karl Friedrich Gauss devised the first one almost 180 years ago. Flux gate magnetometers are very useful devices that measure the change in magnetic field strength as a change in voltage or frequency.
Homemade Aurora Monitor – Part 1 Read More »
9 Minute ReadIntroduction In this post the emission spectra of the Noble Gases are presented. The noble gases constitute the last group (Group 18) in the Periodic Table of the elements. Emission lines obtained from the spectra of these noble gases can be very useful for the calibration of a spectrometer. Historically, these elements were called the
Emission Spectra of the Noble Gases Read More »
5 Minute ReadIntroduction In a previous post we described the Raman Effect and provided a non-mathematical introduction to some of the basic principles of Raman spectroscopy. The final sections of that particular post mentioned some of the recent technological developments in the field of Raman instruments, using small laser modules and efficient spectrometers and filters that allow
Introducing the Thunder Optics Raman Probe Read More »
3 Minute ReadIntroduction The above image is a sample of high purity caesium chloride crystals (CsCl). They are in a sealed glass ampoule and were prepared under high vacuum. At first glance, these appear to be fairly uninteresting plain white crystals, very typical of so many other inorganic and organic salts. But when these crystals are excited
Caesium Chloride and the F Centre Read More »
6 Minute ReadIntroduction The chemical element Selenium. Atomic number 34. Chemical symbol Se. The quirky title I chose for this post – an element that can’t make up its mind – refers to the fact that selenium is generally considered a nonmetal. However, it has also been classed, by many investigators in the past, as a metalloid.
Selenium: An element that can’t make up its mind Read More »
12 Minute ReadIntroduction The humble Bunsen Burner has been a ubiquitous piece of lab equipment ever since it was invented by the German chemist Robert Bunsen in 1855. A testament to its great success is that this very simple and efficient device still continues to be used in science teaching and research labs all over the world.
The Bunsen Burner, the Swan Bands and the Dicarbon Enigma Read More »
3 Minute ReadIn a previous post I described one of the “workhorses” I have been using for several years for recording spectra. This is the Oriel MS125 spectrometer coupled with an InstaSpec IV CCD (Charge Coupled Device) from Andor Corporation. The main limitation of this system was that the software for the detector only ran under DOS
Freedom from DOS at Last! Read More »
7 Minute ReadIntroduction In Part I of this post we briefly described some of the properties of the iodine molecule. The position of iodine in the Periodic Table and its electron configuration was outlined. This determines many of the physical and chemical properties of iodine and its reactivity. We then described some of the spectroscopic theory that
The Iodine Absorption Spectrum – Part 2 Read More »
11 Minute ReadIntroduction Iodine. Atomic number 53. Chemical symbol I. Iodine is the rarest of the stable halogens, if we ignore the radioactive elements Astatine (At) and the recently discovered (in 2010) element Tennessine (symbol Ts). Both are extremely rare and extremely unstable. Iodine is situated in Group 17 of the Periodic Table – for older students
The Iodine Absorption Spectrum – Part 1 Read More »
5 Minute ReadIntroduction Over the years I have gradually accumulated a collection of optical filters. Some of these date back to the days of silver halide photography and are the well-known Kodak Wratten filters that were the workhorse of black & white photographers who needed to enhance, for example, the contrast of landscape photos. Other filters I
Optical Filter Transmission Spectra Read More »
7 Minute ReadIntroduction In a previous post, the phosphorescent properties of several glow-in-the-dark decorative paints were evaluated. The active phosphor in these paints was likely to be europium-doped strontium aluminate. In this post, we examine the emission characteristics of doped strontium aluminate in more detail and record the phosphorescence spectra of these fascinating materials. Some Technical Background
Eu-Doped Strontium Aluminate Phosphorescence Read More »
3 Minute ReadIntroduction The Raspberry Pi is a Single Board Computer (SBC) that has an enormous following online with schoolteachers, hobbyists and for many industrial applications. It was first introduced by the Raspberry Pi Foundation in the UK in 2009 with an original objective to promote the teaching of computer science in schools. Since then it has
The Raspberry Pi Shake & Boom Read More »
7 Minute ReadIntroduction Does anyone remember having glow-in-the-dark stars, planets and constellation stickers that as kids we would stick to our bedroom walls and ceiling? I don’t think I am the only one to remember and enjoy this daily night time event. Once the bedroom light was switched off these stickers would glow green for a while,
Phosphorescent Paints Read More »
7 Minute ReadIntroduction An optical table, or bench, is the optical equivalent of the very popular solderless prototyping breadboards that many electronics hobbyists regularly use to test and develop their electronic circuits. In fact the optical table has sometimes been referred to as an optical breadboard, although optical table or bench are the more conventional terms. But
A Homemade Optical Table Read More »
3 Minute ReadMany years ago, shortly after I obtained my PhD in physical chemistry, I moved from the UK to go and live in France. Basically I had met a French girl whilst living in Bristol where I was a postdoctoral research fellow in the School of Chemistry. Things got serious between us, and I decided to
Who Discovered What and When? A slightly amusing historical tale… Read More »
7 Minute ReadIntroduction There are a number of technical constraints to consider when selecting a spectrometer for a particular application, whether this involves purchasing a commercial model from the wide range of relatviely low cost mini-spectrometers available these days, or whether one is designing and home-building a spectrometer from scratch. In this post we shall consider some
Factors Affecting Spectrometer Performance Read More »
4 Minute ReadIntroduction An off-axis guider is a device well known to all astronomers, professionals and amateurs alike. It usually consists of a compact optical unit inserted between the main imaging camera and the telescope to intercept a small amount of light coming from an astronomical object. Its purpose is to track the motion of that object
Off-Axis Guiders and Sighting Optics Read More »
3 Minute ReadThis is a quick post that examines the spectral line emission changes that occur when a Mercury-Argon (Hg-Ar) gas discharge lamp is switched on and warms up. I used the Time Acquisition mode of an Ocean Optics S2000 fibre-optic spectrometer to record the changes in intensity of 3 spectral lines after the lamp is switched
Mercury Lamp Spectral Changes at Start Up Read More »
3 Minute ReadThe calibration of spectra in wavelength λ that you will see in these different posts has usually been performed with commercial “pencil-type” spectral lamps of mercury-argon Hg(Ar), krypton (Kr) and neon (Ne). These lamps use a continuous AC or DC discharge to excite the inert gases in the tubes and emit a series of narrow
Light Sources for Calibrating Spectrometers Read More »
4 Minute ReadIntroduction Modern spectrometers today, regardless of their size, employ sensitive linear CCD and CMOS sensors. The most popular sizes have 1024, 2048 and more recently 4096 pixels along the dispersion axis of the grating. Associated software automatically reads out a series of digitized values, each value corresponding to a single pixel element on the detector.
Spectrometer Calibration Read More »
13 Minute ReadIntroduction The development of the spectroscope over the last 160 years since its invention has paralleled the evolution in technological advances. This is particularly the case for the last several decades as the development of more efficient electronic detectors have gradually replaced the photographic film. Much progress has been made in this area of detection.
Spectrometer Designs Read More »
5 Minute ReadMeasuring the fluorescence from highlighter pens is always an interesting educational experiment to try and is very popular in schools and colleges to demonstrate the basic principles of fluorescence and spectra. Usually, green, blue or violet laser pointers are used to excite the sample.
Highlighter Pen Fluorescence Read More »
7 Minute ReadI’ll say it again: Raman rules! No apologies because I’m a big fan of his. So who on earth am I talking about? I am referring to the Indian physicist Chandrasekhara Venkata Raman who made a remarkable discovery in 1928 concerning the behaviour of light scattered from molecules. “CV”, as I am somewhat cheekily going
3 Minute ReadIn a previous post we described in scientific terms the basic principles of the optical phenomenon of reflection. The definition of the percentage reflectance of light from the surface of any material was defined quantitatively. We set up a small fibre optic spectrometer and a reflectance probe in order to record the reflectance spectra of
Fruit and Veg Spectroscopy! Read More »
4 Minute ReadIntroduction As its name implies, this spectrometer has a fixed diffraction grating. So the wavelength range available and the resolving power (the spectral resolution) are pre-determined during manufacture. Oriel (now Newport Corporation) used to offer 4 models with different wavelength ranges and resolutions for this spectrometer, but I am not sure if these are still
FICS -Fixed Imaging Compact Spectrograph Read More »
4 Minute ReadIntroduction MS125 This is a very versatile spectrograph that I have used over the years to record a variety of spectra from various emission sources, astronomical objects and other samples. When it is combined with a linear CCD detector such as the InstaSpec IV™ described here it becomes a sensitive and flexible spectroscopy system. The
MS125 and InstaSpec IV Combination Read More »
8 Minute ReadIntroduction This post describes some construction details for an improved version of the SGS spectrometer in what I called the MFSS or Multiple Fixed Slit Spectrograph. The design was intended to overcome several drawbacks of the original, in particular its weight and size: at over 3 kg and a length of over 40cm, this placed
Homemade Spectrometers (Part II) Read More »
7 Minute ReadA few years ago I built a couple of diffraction grating spectrographs. At that time I was a keen amateur astronomer with some degree of traditional photographic, as well as digital, imaging experience. I was hoping (no doubt optimistically and probably naively with hindsight) to connect a spectrometer to my telescope to record the spectra
Homemade Spectrometers (Part I) Read More »
2 Minute ReadIntroduction Several years ago I connected the MS125 spectrometer to a 12 inch Meade LX200 telescope to test its suitability for recording stellar spectra. In order manually to guide on the star’s image the Oriel Sighting Optic was employed which you can clearly see in the photo here: Exposure times were limited to under 5
Some Early Stellar Spectra Read More »
5 Minute ReadReflection is simply the return of a light ray from any surface without any change in wavelength. It is also referred to as Reflectance, defined as the effectiveness of any material in reflecting (returning) radiant energy of any wavelength, not just visible light. It comes in two types: (1) Specular Reflection, in which the angle
Diffuse Reflectance Spectroscopy Read More »
9 Minute ReadWhat is Fluorescence? Before we can consider what actually is called fluorescence, we must mention the general process of luminescence Luminescence can be generally defined as any emission of light (electromagnetic or ionizing radiation) from any substance that is NOT caused by thermal heating of that substance. Yes, I know, that sounds a bit dry.
3 Minute ReadAbsorbance In very general terms, Absorption Spectroscopy is the spectroscopic technique that considers what happens when electromagnetic radiation of any wavelength passes through a material and some of these wavelengths are absorbed by the substance under study. Very often, visible light is used to analyse the material and the most common substances examined are
Absorption Spectroscopy Read More »
