Columns | Column: The Baseline

The history of how the atomic number came to be

A logarithm is a mathematical function that shows up in some forms of spectroscopy. Understanding what it is can give us a better appreciation for its function in our fields.

A detailed look at what makes the sky appear blue in color, using Rayleigh scattering, Maxwell's equations, and the Mie theory.

A reminder of what certain terms mean and how they should be used in scientific work

A look at how fluorescent lights are spectroscopically different from the old-fashioned incandescent light bulb.

Here, Maxwell's fourth equation of electrodynamics and how light is described in terms of Maxwell's four mathematical expressions is examined.

Results are generalized from the last installment and considerations are made for how it applies to one of Maxwell's equations.

Here, we continue the discussion of electromagnetism and Maxwell's second equation.

A discussion of magnetism, leading into Maxwell's second equation

Here's the fundamental calculus you need to understand Maxwell's first equation

In the realm of classical physics, Maxwell's equations still rule, just as Newton's equations of motion rule under normal conditions.

The historical developments leading up to Maxwell's equations are discussed in Part I of this series.

Virtually everything we know about stars is based on spectroscopy, including what we know about magnitude, red shift, and why the night sky is dark.

Not all spectroscopy uses light . . .

Here, we continue our treatment of symmetry and group theory by introducing a very useful mathematical tool in group theory. It has two names in common use, but thankfully they both have the same acronym: GOT.

David Ball celebrates the 150th birthday of spectroscopy.

In the third part of this series, David Ball starts getting into the mathematical aspects of group theory, aspects that ultimately become useful in spectroscopy.

In the previous installment of this column, David Ball introduced the five types of symmetry elements that are important in physical science. Here, he discuss why it’s called "group" theory in the first place.

Group theory is the field of mathematics that includes, among other things, the treatment of symmetry. Well, it turns out that molecules have symmetry, so group theoretical principles can be applied to molecules. Because spectroscopy uses light to probe the properties of molecules, it might not be surprising that group theory has some application to spectroscopy. Here, we start a multipart discussion of symmetry and group theory.

Columnist David W. Ball discusses how a scarf featuring the visible emission spectrum of hydrogen inspired his latest column, on color.

Some forms of spectroscopy involve actions other than measuring a property of light. In the case of this form of spectroscopy, the energies of emitted electrons are measured.

In the previous installment of this column, David Ball introduced the concept of base units and discussed several of them. Here, he completes the discussion of the units themselves and presents some associated issues.

Columnist David ball discusses the history of the units system used by scientists and several of the base units themselves.

In the last installment of this column, I discussed prisms. In this installment, we will consider their curved cousins.

A prism is an optical component that serves one of two major functions: it disperses light, or it modifies the direction (and sometimes polarization) of light. In some cases, a prism has more than one function, and they are discussed here.

In Parts I-III of this series, columnist David W. Ball recounted the failings of classical mechanics, the quantum hypothesis, and the rise of a new theory called quantum mechanics. In this installment, he discusses the ideal systems whose wavefunctions can be determined exactly from the Schr?dinger equation.

Columnist David W. Ball discusses the pioneering work of Erwin Schrodinger, whose work on wave mechanics forms the basis of the modern understanding of subatomic behavior.

In part I of this series, columnist David Ball laid the groundwork for why the scientific understanding of nature in the late 19th century was found wanting: it could not explain a variety of phenomena that scientists were examining. (One of these phenomena was spectroscopy itself!) In this installment, he reviews the paradigm shifts in science that preceded the development of the currently accepted theories of the nature of matter. It all starts with the nature of light.

In this first part of a multipart series, columnist David Ball reviews the failures of classical mechanics that necessitated the development of a new theory of nature.

Columnist David Ball discusses the search for light sources that are more energy efficient than incandescent light bulbs. In particular, he focuses on light-emitting diodes.

Columnist David Ball discusses the fact that spectroscopy is based upon light and considers the spectroscopy of fire and flame.

David Ball discusses how the electromagnetic spectrum was originally mapped out and what this means for spectroscopy.

In the previous installment of this column, the author discussed clocks as the first scientific instrument. What do clocks have to do with spectroscopy? Actually, the world's most accurate clocks, atomic clocks, are based upon a spectroscopic transition of cesium or other elements, making spectroscopy a fundamental tool in our measurements of the natural universe.

After due consideration in his copious free time, columnist David Ball comes to the conclusion that the world's original scientific instrument was the clock. This might provoke a question: What does it have to do with spectroscopy? The answer might surprise readers.

September 2006. An unusual form of spectroscopy uses light and sound to probe the behavior of materials. Here is a brief introduction to photoacoustic spectroscopy.

The issue of whether light is a particle or a wave was an important historical debate. The actual answer is still unnerving to some people. Here, we will explore the history of this question and present the modern interpretation of the nature of light.

Getting light from one place to another is a key task in any spectroscopic method. Sometimes we send light through (mostly) empty space using mirrors or lenses, and sometimes we use things called fiber optics. This installment of "The Baseline" tackles fiber optics.

Some types of spectroscopy work better if the intensity of the light source increases and decreases in a regular pattern. Such a varying signal is called modulated, and here, the author explores the devices that perform this function.

Spectroscopists separate light from the sun into spectra and look for the presence or absence of particular lines that give hints regarding its chemical composition. The same method can be applied to studying the composition of other matter in the universe.

The author presents a discussion of the operation and optical complexities of the human eye.

The author provides a brief historical and technological review of different types of telescopes, and how they were developed and improved.

A relatively new technique with a growing number of applications, dichroism spectroscopy is based upon the fact that a sample interacts with the same wavelength of light having different circular polarization in different ways.

The author discusses photoelectron spectroscopy theory and describes radiation sources used in the technique.

Columnist David Ball explores Mössbauer spectroscopy.

Columnist David Ball explores Mössbauer spectroscopy.

This installment concludes the author's three-part series by discussing the spectroscopic applications of the Raman effect.

Theory of Raman Spectroscopy