Posted in Education, Physical Chemistry, Science Education, Spectroscopy, UV-VIS-NIR, working problems

Spectrum of a Particle in a 1D Box

It is safe to say that every physical chemistry course teaches the Particle in a Box problem as an introduction to quantum mechanics. I have taught it also in my course for years.

I have been bothered for years, however, by the fact that the text books stop after solving the Schrodinger equation. All of them that we have surveyed do this. McQuarrie, Atkins, Engel, Levine, etc.

This is a shame because we can’t detect the energy levels by themselves. Quantum theory was invented to explain spectroscopy. So why not take the 1D Particle in a Box (1DPB) problem all the way to a simulated spectrum?

At SHSU, we do.

Here are three lectures that explain what I do with the Particle in a Box.

(Be patient with the Kahoot quizzes and end of class Q&A. Feel free to skip ahead, or try to answer the questions in your own mind to see how you do! To find all my Kahoot content search for my username chem_prof on Kahoot. I have Quantum, Thermo, and Forensic Chem Kahoots.)

Lecture 1 – Managing the Messy Mathematics

This lecture takes the spectrum of a 1DPB apart to show what pieces of the spectrum are explained by quantum theory.


Lecture 2 – The Schrodinger Equation

This lecture is the traditional presentation of the 1DPB problem – normalizing the wave functions and solving for the energies via the Schrodinger equation.


Lecture 3 – Spectral Transitions and Spectral Assignments

This lecture discusses spectral transitions, the transition moment integrals and the transition equation which tells us about the spacing of our spectral lines. The transition equation also tells us about the quantum system if we begin with an experimental spectrum and assign the quantum transitions.


What are your reactions to this approach? I’d love to hear from you in the comments section. I am preparing this material for a book for students to read in the summer prior to taking pchem. I think it will greatly help to get them thinking about our quantum world early and often.

Happy Pchemming!

Darren Williams

Posted in Contact Angle, Critical Solution Temperature, D L Williams, DSC, Education, Forensics, FTIR, Hansen Solubility Parameters, LIF, Physical Chemistry, Raman, RER, Science Education, Solubility, Solvent Blending, Spectroscopy, Thermal Analysis, UV-VIS-NIR, XPS

PCHEM and Forensic Chem Lecture Videos

I frequently have seniors who want to revisit the concepts in pchem sit in my 8AM lectures the year after they have had my course. It’s a privilege to have them and an encouragement to see their natural curiosity in action. They seek to firm up their understanding of the quantum world and how we interact with it (i.e. spectroscopy).

In the fall of 2017, I put these students to work videoing the lectures and posting them on the Physical Chemistry at Sam Channel. These videos are essentially raw footage of lecture. The videos could have been greatly improved by adding in the PowerPoint Slides, captioning, cleaning up the audio, and cutting out my “ums” and “uhs”. But these volunteers did not have time to do that, nor did I. I had a CLEANING WORKSHOP to plan and execute!

CHEM 4448 – Physical Chemistry 1
– Quantum Mechanics and Spectroscopy


CHEM 4449 – Physical Chemistry 2 -Thermodynamics


CHEM 4380 – Forensic Chemistry

The students appreciated the fall lecture videos so much, there was a great amount of interest in capturing the Forensic Chemistry Lectures. So we created a Forensic Chemistry at Sam Channel, too.


The lecture playlist is only one piece. Jessy also created other playlists of videos on the Forensic Chemistry at Sam Channel that should interest Forensic Science and Forensic Chemistry students and enthusiasts. She performed these tasks as an SHSU Honors Contract for the course – an activity that supplements the material for the student and enhances the skills that they take away from the course.

Thanks to the Student Team!

Even raw footage must be stitched together, uploaded, described, tagged, and set up on YouTube. This takes TIME and time is a valuable commodity for our chemistry majors.

I thank William Fernandez for videoing CHEM 4448 and CHEM 4449. His videos were so well-received by the students that Jerome Butler decided to sit in and video my Forensic Chemistry course CHEM 4380. Thanks Jerome!

I thank Matthew Peavy for producing the videos for CHEM 4448 and CHEM 4449, and for uploading them. I thank Jessy Stone for producing and uploading the CHEM 4380 videos for Forensic Chemistry.

You students who are willing to go beyond the minimum give us hope for the future.

You people in industry and in graduate programs, hire these students! You won’t be sorry!


Posted in Education, Spectroscopy, UV-VIS-NIR

What makes a rainbow?

All of us love a rainbow, and a double rainbow is even more exciting. This is pchem* in action!

A double rainbow photographed in Karlsruhe on July 22, 2011. Leonardo Weiss

You may have noticed that rainbows only appear with the sun at your back. Why?

Rainbows are angle-dependent. The light coming from behind you hits water drops of a particular size and at a particular angle so that they are diffracted (bent) inside the drop. This can occur in a clockwise or counter clockwise manner. The clockwise path through the drop to your eye and the counter-clockwise path occur at slightly different angles. This creates the two rainbows.

The different wavelengths of light from red to blue also travel at slightly different angles (just like through a prism), and this creates the spread of colors in each rainbow.

Have you ever seen a triple or higher-numbered set of rainbows?

Some will brag and say they have. But this is extremely improbable. If their eyes were sensitive enough to see this higher-order diffraction, then they would be blinded by the bright sunlight needed to produce the rainbow in the first place. The probability of light traveling multiple circles within the water drops to create second- (and higher-) order diffraction effects is very slim compared to the single pass rainbows that we are all familiar with.

Post links to your favorite rainbow images in the comment section.

Subscribe to this blog for more Pchem* topics.

*Pchem (Physical Chemistry) is the study of the physical properties of the universe.

Posted in Contact Angle, D L Williams, FTIR, Hansen Solubility Parameters, Physical Chemistry, Raman, Solubility, Solvent Blending, Spectroscopy, UV-VIS-NIR, XPS

Corporate Research Funding in Uncertain Times

Some points that describe the current R&D funding climate:

  • Continued uncertainty in corporate R&D hiring
    US non-financial corporate cash holdings rose to $1.24 trillion at the end of 2011 according to Moody’s. One reason among many is a reluctance to hire until the uncertainty surrounding benefits costs is reduced.
  • Tightening of government funding of university R&D
    The US government still funds a significant amount of chemical research, but competition for those funds is increasing greatly. The growing deficit must eventually have an impact on the availability of funds for chemical research.

As a physical chemist, I am partial to APPLIED chemistry research, and the interactions I have had with corporations and government contractors have been enjoyable and fruitful for both parties.

I have prepared this blog post and my new “Sponsors Page” on my university website to actively address the R&D needs of corporations and government contractors.  Many of these entities are under a hiring freeze, and yet, their chemistry-related problems continue unaddressed.

When I worked for a government contractor, I dealt with these issues:

  • “I could solve this problem in 6 months, if I didn’t have to support production, also.”
  • “I’d love to hire someone to research this and other issues but
    1) we are under a hiring freeze,
    2) we don’t have the budget for a whole person (1.0 FTE),
    3) we can afford the salary but are reluctant to commit to an unknown fringe benefit committment,
    4) we can afford a science temp, but we need a Ph.D. chemist.”
  • “Maybe a university researcher could help, but there’s no telling what an Ivory Tower Pinhead is going to spend our money on.  And, what would we have to show for it?”

To quote a recent President, “I feel your pain.”  But not all residents of the Ivory Tower are Pinheads.  Here are the benefits of funding an APPLIED-SCIENCE-MINDED university professor and his students to address your problem.

  • Academic salaries for Ph.D. chemists ($70k, 2012 median) are 65% of that in Industry ($107k, 2012 median) according to the ACS Employment Survey, so renting a brain is potentially cheaper than buying one.  Often these are 9-month salaries, but this annualizes to $93k, which is $14k less than the industry median 12-month salary.
  • Academic chemists are able to spend 100% of their effort on your problem during the summer months.  If the median salary of $70k is for 9-months, then funding this scientist for three full months in the summer is only $23k.  Universities tack on varying amounts of overhead and fringe benefits costs to this number so the actual costs will be more like $40k ($85 / hr all-inclusive).  This is still a very reasonable amount for 3-months of a PhD chemist’s time.
  • Academic institutions have an amazing array of instrumentation that your company could not justify purchasing.  The overhead costs tacked onto the academic chemist’s labor rate is the price of admission to the instrumentation lab or computational facility.  Our lab charges consumables costs on a per-day or per-sample basis in the range of $20.  This may seem to add up, but so do the costs of solvents, vials, etc.
  • Academic institutions are FULL of eager chemistry majors who LOVE to study research problems that are “real life”.  These students are also inexpensive when compared to hourly chemical technicians.  A typical student will have a fully-burdened (with overhead) rate of $20 per hour all-inclusive.  These students will graduate with a working knowlege of your industry and will be excellent prospects for future hires.

The number-one factor to consider is the principal investigator (PI).  Does he or she understand your problem?  Have they done similar work in the past?  I have turned down funding because I did not think I could deliver value to the sponsor.  Find someone who understands your terms, your culture, your requirements, and the practical aspects of implementing the ideas proposed.

If your interests are in any of these areas, I’d love for you to contact me.

  • Cleanliness verification, contact angle measurements, coupon tests
  • Solvent properties, surface tension and hydrostatic densities, Hansen solubility parameters vs Hildebrand solubility parameters
  • Solvent blending, solvent blend prediction, miscibility
  • Solvent substitution, reduction of hazards, reactivity, ozone depletion potential, or global warming potential
  • Material compatibility, polymer stress cracking, polymer swell, polymer processing solvents
  • Recrystallization and crystal morphology control based upon non-solvent interactions
  • High-explosive detection, solubility, modeling, spectroscopy, recrystallization, precipitation, and PBX production/processing
  • Spectral assignments and predictions (FTIR, Raman, UVVIS, XPS)
  • Computational chemistry, ab initio, density functional theory, quantitative structure property relationships (QSPR/QSAR)
  • Six-Sigma Blackbelt – consulting services

There are ways to continue innovating in the current business climate.  I’d love to help if I can.


Posted in Education, Physical Chemistry, Spectroscopy, UV-VIS-NIR

Quantitative Color

I have always been bothered by subjective references to color, especially when used in acceptance specifications or quality evaluations.  One specification spelled out that the product must be burnished gold.  Great.  What exactly is burnished gold. 

This sent me down the path toward colorimetry, and since this was lacking in my B.S. and Ph.D. chemistry curricula, I decided to include it in the Physical Chemistry course at Sam Houston State University.  Here are the abstracts for two articles I wrote for the Journal of Chemical EducationContinue reading “Quantitative Color”