Workshop 2: Spectrometry & Building a Spectrometer

Drafted by Gretchen Gehrke, Stevie Lewis, Liz Barry.

Why (The Situation): We want to learn what spectroscopy is, and we want to understand the purpose spectroscopy serves in environmental science. We want to join the development community around Public Lab’s prototype spectrometer and work toward realizing its promise of collecting data that will be useful in pollution cases.

When: 2.5 hour workshop, part of a four-part series.

Where: a room with long tables, chairs, power outlets, water source, and internet connection.

What (the Content): what kinds of things can be learned from light; how to measure a rainbow; what the unit “nanometer” refers to; the working parts of a spectrometer; how to position a sample in front of the spectrometer.

For What (Achievement Based Objectives): In completing this four hour workshop, you will:

• Meet others attending the workshop
• Share with each other what motivated you to to participate
• Read 4 brief stories from spectrometry experiments in environmental science
• Measure a rainbow (in nanometers!)
• Study what wavelengths belong to which colors
• Fold paper pieces into a working spectrometer
• Fold paper pieces into a holder for lasers and sample containers
• Critically review the documentation you were provided -- what worked, what didn’t?
• Post your critical review as a research note on publiclab.org

Notes for Facilitators:

Estimated Time: 2h 30min.

Materials Needed:

• large clean space for people to build their kits (long tables work well)
• 2 poster boards one with the words “Notes” “Questions” “Ideas” evenly spaced down the left hand side.
• large chart paper
• markers and pens
• sticky notes
• paper research notes https://i.publiclab.org/system/images/photos/000/005/815/original/paper-research-note.pdf
• a shallow pan
• water (enough to fill the pan with 2in of water)
• a small mirror
• a flashlight
• a piece of white paper
• one computer per person or team constructing the spectrometer
• internet connection
• a power source that can support all your computers
• one Public Lab Spectrometer (version 3.0) and oil testing kit addition per person or team
  • The oil testing kit add-on pieces can be found on these download files that you can print out on heavy card stock or a cereal box and cut the pieces out.
  • (https://i.publiclab.org/system/images/photos/000/009/589/original/all-together-9-8.511.pdf),
  • here (https://i.publiclab.org/system/images/photos/000/011/023/original/light-flap.svg)
  • and here (https://i.publiclab.org/system/images/photos/000/013/171/original/all-together-10-2.pdf), a camera (to document)

Setting up the event:

• Set your tables up near a power source that can be used by all the computers
• Put up the 2 poster boards on the wall. One poster board will be blank, on the other, put the words “Notes, Questions and Ideas” evenly spaced down the left hand side.
• Put post-its, markers and pens on each table.
• Put copies of the hand written research notes on each table for people to include more in depth information on what participants explored.
• Set one Spectrometer kit, one Oil Testing Kit (or the supplies for these), and one computer, on each station people will work from. (Suggested group size is 2-3 people -- you can divide your chairs, tables and participants up accordingly)

Workshop Schedule

1. Introduction (20 minutes total)
   1. Who’s in the room (10 minutes)
   2. Introduction to the event (10 minutes) 2: Learning about Spectrometry (25 minutes total)
   3. Seeing in color
   4. Explore and measure a rainbow (activity from physicscentral.com) (20 minutes)
   5. What we can learn from light (5 minutes)
2. Use of spectrometers in environmental science
   1. Background Reading
   2. Defining your problem
3. Building your Spectrometer (1 hour 20 minutes)
   1. Tools you will need
4. Reflection and wrap-up (10 minutes)

Workshop Outline

1. Introduction

1.1 Who is here today?

As a whole group, take turns introducing yourself by saying your name, where you’re from, and your reason for coming to the workshop today.

1.2 What are we doing today?

Take a minute to read through the achievement based objectives on page 1 of your handout.

1. If you have not done so yet, introduce yourself:
   1. why you are interested in this project and
   2. a little bit about Public Lab.
2. Give an overview of the event goals and structure (at the top of this page)
3. Emphasize “the tools, technology and learning that happens here is always under development. One of the major outcomes of the event is to provide constructive feedback on the learning, the activities and the tool we will build in order to improve it for future participants.”
4. Introduce the things in the room:
   1. Highlight the posters, markers and sticky pads available for people to put up their questions, comments, and ideas on as they work through the event.
   2. Identify the paper research notes for those who would like to take in depth notes on their steps for sharing back with the Public Lab community.

2: Learning about Spectrometry

2.1 Seeing in color

Choose one person to read out loud:

“Light is made up of waves, and we see longer waves and shorter waves as different colors.” - Randall Munroe in Thing Explainer: Complicated Stuff in Simple Words, 2015.

When light is bent (AKA refracted), each color will separate out according to its wavelength at a different angle. 

Let’s explore this idea in the next task.

2.2 Explore and measure a rainbow (20 minutes)

This activity is taken from physicscentral.com - Aliya Merali

Resources needed: A shallow pan, water, small mirror, flashlight, paper

• Fill the pan with 2 inches of water
• Insert the mirror at an angle and hold the paper above the mirror
• Shine your flashlight at the intersection on the water and the mirror as shown below:

http://physicscentral.com/experiment/physicsathome/rainbow.cfm

Choose a person at each table to read each of the following sentences out loud, pausing frequently for discussion:

The light coming from the flashlight is refracted by water (which means the water is acting like a prism), then reflected by the mirror onto the paper above. 

Question for the group: In what order are the colors displayed? Have you ever seen a rainbow in a different order of colors?

nm = nanometer, which is one billionth of a meter

Rainbows manifest from violet to red. Why? Because colors travel at specific wavelengths: violet has the shortest wavelength we can see, blue is slightly longer, and green slightly longer all the way up to red, which has the longest wavelengths that humans can see. 

Fun fact: wavelengths can be measured … in nanometers! Red is in the 620–750 nm range on the visible spectrum whereas violet is always in the 380–450 nm range. This is what this looks like on a chart:

https://en.wikipedia.org/wiki/Light

Although most of us can see colors with the naked eye, generally, humans are not very adept at measuring color or color intensities.

A spectrometer is a device which splits colors apart, like a prism, and measures the strength of each color. 

In its simplest form, a spectrometer is an optical device, like a prism, which separates light into separate wavelengths so you can observe and measure the amount of light energy at each frequency. For more information, see the [spectrometer curriculum](/wiki/spectrometer-curriculum).

Look at the example of soybean oil below:

https://spectralworkbench.org/spectrums/44929

Notice how much of each color this particular soybean oil is giving off. The peaks and dips in the chart that show the intensity of that particular color. Consider, how can this be useful? One possible use for this is that although Crude Oil and Synthetic gear oil 80w90 often appear to our human eyes to be the same color, they are two different substances. Below, see an example of how a spectrometer can read their spectral signatures more precisely than our human eyes:

https://spectralworkbench.org/sets/3144

2.3 What we can learn from light (5 minutes)

The wavelengths of light absorbed by, reflected off, or emitted by matter can be used to identify what the matter is composed of. Different materials (whether liquid, solid, or gas) that appear the same to the naked eye can actually be distinguished by the colors we can measure from them with a spectrometer.

Discuss the following question as a group, and have a note-taker write down what people say under the “ideas” section of the poster board:

• Does the information about give you any ideas about how could a spectrometer be useful?

Check out some examples that other Public Labbers have explored with a spectrometer: https://publiclab.org/wiki/spectrometry-activities.

------ (10 minute break) ------

3. Use of spectrometers in environmental science

3.1 Background reading (45 minutes)

Read these short synopses about how spectrometry has been used in environmental science, and what types of data and advocacy can result from the use of a spectrometer.

One sentence overview: Fluorescence spectroscopy is a widely useful technique. Similarly to how blood or bodily fluids at a crime scene are revealed by shining a UV light, oil also fluoresces. 

https://publiclab.org/notes/eustatic/4-20-2012/370nm-uv-detection-corexit-dispersed-oil-gulf-coast-beaches

From the texbook, Oil Spill Science and Technology chapters 4, 5, 7, we learn about more about this method to identify oil in the environment:

The combination of spectroscopy and UV lasers is used to identify oil in the environment. Oil has a “unique oil fluorescence spectral signature” (p 171); when ultraviolet light (300 to 355 nm) is shined on petrochemicals, they fluoresce (release) light in visible wavelengths that are specific to the kind of oil it is. Chlorophyll and other biological materials also fluoresce, but (fortunately) at significantly different wavelengths to avoid confusion. 

From the abstract of the 2012 article, “Findings of Persistency of Polycyclic Aromatic Hydrocarbons in Residual Tar Product Sourced from Crude Oil Released during the Deepwater Horizon MC252 Spill of National Significance” produced by James H “Rip” Kirby III, of the University of South Florida Dept of Geology, and also of The Emerald Coast Chapter of Surfrider:

The use of ultraviolet light equipment in the field showed distinct fluorescent responses to illumination by a 370nm UV light source. UV light equipment was found to be very efficient in identifying tar product on the beach for evaluating the visual level of contamination on the beach. Fluorescent responses from tar product found in the field and laboratory created tar product were measured by fluorometry equipment. [link](http://surfrider.org/images/uploads/publications/Corexit_Connections.pdf)

From the 2012 article, “State of the art satellite and airborne marine oil spill remote sensing: Application to the BP Deepwater Horizon oil spill”, we learn how different methods are used in times of a spill:

This technical article begins by stating how valuable people are in times of disaster: “experienced observers are a spill response’s mainstay.” Since there are few experienced observers available, and the weather and environmental conditions present access challenges to getting a holistic view of the situation, responding to the Deepwater Horizon oil disaster also involved extensive airborne and spaceborne passive and active remote sensing. An airplane carried a Visible/Infrared Spectrometer over the spill to derive oil slick thickness and oil-to-water emulsion ratios. Other equipment on planes and satellites helped extrapolate this understanding to the geographic extent of the entire spill, find the extent of burned oil carried into the air as smoke, and track oil as it sunk to the seafloor. http://www.sciencedirect.com/science/article/pii/S0034425712001563 

There was a January 2016 discussion on the plots-spectrometry mailing list that referenced the 2011 article "Prediction of crude oil properties and chemical composition by means of steady-state and time-resolved fluorescence." by p.3600 of Pantoja, Patricia A., et al. Energy & Fuels 25.8 (2011): 3598-3604:

This graph from the article shows peak shift due to dilution of crude oil:

Public Lab Oil Testing Fellow Ethan has been working on a dilution test to see if diluting oil samples with mineral oil changes their spectrum, and if there's a way to adjust for that. The main gist of this article is about exactly the kind of fluorescence based oil differentiation we're attempting with the Oil Testing Kit. They use a 337nm excitation light source, not the 405nm that Public Lab has been working with, but the peaks in the graph occur at wavelengths longer than 405nm, so some active developers of the spectrometer feel this is not improbably related to the blue=>red shift we're looking for in lighter=>heavier oils:

As a group, discuss these brief summaries and your ideas.

3.2 Defining your problem

Workshop 1 covered what is required in designing a scientific experiment. So far, this workshop has presented how spectroscopy is used to detect oil in the environment. Now we will put these elements together. Below are options for what kinds of experiments are known to be possible with the current state of development on Public Lab’s spectrometer 3.0 and oil testing kit. Discuss as a group which topic you would like to design an experiment around:

• If you have an unknown substance you think might be oil, you can tell if the substance definitely isn’t oil.
• If you have different oil samples, you can compare and contrast these samples (for example diesel, crude, fish, and motor oils).
• You can compare known oil samples with an unknown sample. You should be able to say if your unknown sample has a spectrum similar to or different from your known sample.
• You can compare oily materials to tell if they are similar or different.

After the group has chosen which experiment they would like to design, design a hypothesis (if needed, refresh your memory by reviewing Workshop 1: 2.3 and 2.4). Record the hypothesis on the large chart paper so that everyone can see it. Discuss as a large group.

Return to small groups and work through designing the experiment. Ask yourselves, what needs to be done to test the hypothesis? Record the steps you specify for the experiment on the large chart paper.

4 Spectrometer Construction

4.1 Tools you will need (1 hour 20 minutes)

In small groups, or individually, you will build both the spectrometers and the oil testing add on pieces by following directions and photographs online. These pieces will fit together and are your tools for oil testing. As you build the spectrometer and have ideas for how the pieces or the instructions could be improved, add your ideas to the board with sticky notes.

Begin by gathering these materials:

• Spectrometer Kit, per person or team
• Oil Testing Kit add on, per person or team and (for this part you only need the paper pieces and the laser.)
• One computer with internet connection, per person or team
• Scissors

Go online to find instructions for:

• constructing the spectrometer: http://publiclab.org/wiki/desktop-spectrometry-kit-3-0
• assembling the oil testing kit: http://publiclab.org/wiki/oil-testing-kit-construction

Enjoy building!

5. Reflection and Wrap up (10 minutes)

Send one person from the entire group to take notes on the poster board while everyone reflects on the day’s activities through the following questions:

• what was hard?
• what was easy?
• what questions are you left with?
• what questions are you inspired to explore?
• any other takeaways you’d like to share with the Public Lab community?

Choose someone from the group to write up their experience as a Public Lab Research Note.