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Tips for Better Fluorescence Data

Elaine using the Fluorescence spectrometer

Fluorescence spectroscopy is a very sensitive and delicate technique. It often requires a few attempts before getting great data. In our chemistry department, we have come across a few common problems and would like to share some solutions that fix or avoid them.

While these helpful tips are designed for improving your Vernier Fluorescence/UV-VIS Spectrophotometer data, the majority of them can be used with any combination fluorescence/absorbance spectrometer.

  1. Collect an absorbance spectrum of your sample first. This will help you decide which excitation wavelength will work the best for your application. It will also help you narrow down the concentration of your sample for fluorescence measurements.
  2. If the absorbance reading where you plan to excite it is greater than 0.1 absorbance units, dilute your sample until it is around 0.1. Fluorescence is a very sensitive technique and requires samples to be more dilute than absorbance measurements. If samples are too concentrated, you may see low fluorescence emission peaks and/or distorted band shapes. This is due to the inner filter effect which is the reabsorption of emitted radiation.
  3. Try different sample time/integration times. The sample time is the time that the individual diodes (pixels) in the array are allowed to respond to light before they are “read out” and reset to zero. They respond linearly to light until they approach saturation. When students increase and decrease this value, the signal will get larger and smaller proportionally. In Logger Pro, you can adjust this value during live data collection to see the result.
  4. Change the LED Intensity. This is similar to adjusting the slit width in a typical fluorescence spectrometer. Increasing the intensity should increase the signal.
  5. Change the Samples to Average. This command sets the number of discrete spectral acquisitions that are accumulated before a spectrum is displayed. The higher the value, the better the signal to noise ratio. The drawback here is that the more samples your students are averaging, the longer they are going to have to wait for a stable spectrum.
  6. Make sure you are using Logger Pro 3.15 or newer, or LabQuest 2.4.2 or newer. In older versions, you are forced to calibrate in fluorescence mode. There is a bug during fluorescence calibration that does not honor the sample time you typed in before the calibration. This will cause spectra to look much smaller than you may anticipate. If you chose to calibrate even in later versions, you will see this bug; the short-term fix is to change the sample time after calibration.

To get acquainted with the Vernier Fluorescence/UV-VIS Spectrophotometer software and instrument, we suggest following the free lab instructions for “A Guided Inquiry Approach to Understanding Fluorescence Spectroscopy“.

The experiment walks through a lot of common sticking points and really helps students understand what they are looking at when taking fluorescence data.

Want to see more? I will be showing off the Vernier Fluorescence/UV-VIS Spectrophotometer at the Fall Regional ACS shows (MWRM, SERMACS, and SWRM) as well as at WCCTA. See a full list of the college chemistry conferences we attend »


Upcoming Conference Schedule for Vernier

Vernier booth

By participating in many regional and national trade shows each year, Vernier Software and Technology provides current and future customers with many opportunities to personally experience our products and services. It’s a great way to review the features of the latest Vernier products, or to bring any technical matters or applications questions to our attention. See our upcoming chemistry conference schedule below.

We also offer free Professional Development Workshops that include hands-on Vernier equipment training to help you integrate data-collection technology into your science curriculum.

NSTA Recommends Takes the Vernier Go Direct® O2 Gas Sensor on a Flight

NSTA Recommends recently featured the Go Direct® O2 Gas Sensor. In his review, Martin Horejsi used the wireless sensor to collect data during various investigations, including an out-of-the-classroom experiment on an airplane. He highlighted the sensor’s features, plug-and-play functionality, and overall ease of use.

Photo of Go Direct O2 Gas sensor tucked in seat pocket for data collection.
A student, who was travelling with Martin Horejsi on a trip to a NASA facility, collected data with Go Direct O2 Gas while on an airplane. The Go Direct O2 Gas Sensor is tucked into an airplane seat pocket. (Image provided by Martin.)
Graph of oxygen gas levels in airplane cabin during approach for landing
The oxygen gas level in the cabin rose upon the plane’s approach for landing. (Image provided by Martin.)

In the review, Martin says:

“With [the] new Go Direct® O2 Gas Sensor, the ability for students to measure relative oxygen concentration has never been easier or faster.”

“As a wireless probe the Vernier Go Direct® O2 Gas Sensor provides all the necessary capabilities of an O2 sensor with none of the pesky cables that limit use, knock over experiments, and require an additional interface.”

He concludes by saying:

“The Vernier Go Direct® O2 Gas Sensor pushes the boundary of experimental measurement forcing a teaching evolution beyond the analog. We can now fulfill the dream as science teachers to where our students leave us behind as they accelerate past us.”

The Go Direct® O2 Gas Sensor measures gaseous oxygen concentration levels and air temperature. It is part of the complete Go Direct family of sensors that offers teachers and students maximum versatility to collect scientific data either wirelessly or via a USB connection. These low-cost sensors can be used in more than 300 teacher-tested experiments developed by Vernier and are supported by free graphing and analysis software, the Graphical Analysis 4 app.

Read more about the Go Direct O2 Gas Sensor on NSTA Recommends »

Vernier Go Direct® Sensors Win a 2018 Tech Edvocate Award

The Tech Edvocate Awards 2018 Winner Logo

Our Go Direct family of sensors, along with Graphical Analysis 4, recently won a 2018 Tech Edvocate Award. The family of wireless sensors and its accompanying software were recognized in the Best STEM/STEAM Education App or Tool category.

After an initial round of online voting by educators, finalists and winners were ultimately selected by a panel comprised of two edtech thought leaders, two pre-K through 12th grade teachers, one college professor, two K through 12 administrators, one college administrator, and two pre-K through 12th grade parents. The winning products were chosen based on the extent to which they are transforming education.

The complete Go Direct family of sensors offers teachers and students maximum versatility to collect scientific data either wirelessly or via a USB connection. These low-cost sensors can be used in more than 300 teacher-tested experiments developed by Vernier and are supported by free graphing and analysis software, the Graphical Analysis 4 app.

Learn more about Go Direct sensors and Graphical Analysis 4 »

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