| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| warren | "Related: How can we detect contaminants in water samples with a DIY spectrometer using reagents? https://publiclab.org/notes/warren/12-18-2017/ca..." | Read more » | over 6 years ago | |||
| warren | "Also noting that @ygzstc cited some work supporting the use of the area under the curve in a spectrum data reading instead of intensity at one wave..." | Read more » | over 6 years ago | |||
| warren | "Just to clarify here, I believe to sum up we can say that: IF a reagent reacts linearly (for example, if doubling the concentration of the thing t..." | Read more » | over 6 years ago | |||
| warren | "Copying in answer from @stoft, here: It is my understanding that Beer's law is not the relationship between reagent's effect on color, but is the ..." | Read more » | over 6 years ago | |||
| warren | "Just another note here -- starting to look for someone interested in creating an activity out of a beer's law demonstration -- for determining conc..." | Read more » | over 7 years ago | |||
| stoft | "@warren has a good point; the smaller the change in transmitted light (as a function of attenuation caused by concentration change) the greater the..." | Read more » | almost 8 years ago | |||
| gretchengehrke | "Hi @FoxClass, This is a great question. As the other commenters have mentioned, to compare intensities across different wavelengths, an intensity ..." | Read more » | almost 8 years ago | |||
| warren | "However, if it's possible to either turn off exposure compensation between your two scans, or to scan both spectra at the same time (side by side),..." | Read more » | almost 8 years ago | |||
| warren | "Yes, as @stoft mentions, an absolute intensity calibration is not required for demonstrating the Beer Lambert law; @mathew refers to a post about g..." | Read more » | almost 8 years ago | |||
| stoft | "The Beer-Lambert law primarily states there is a relationship between attenuation and wavelength of light through a substance. The attenuation is l..." | Read more » | almost 8 years ago | |||
| mathew | "The spectrometer requires intensity calibration in order to detect color consistently. The active research is here: https://publiclab.org/notes/st..." | Read more » | almost 8 years ago | |||
| straylight | "thanks ygzstc, that makes sense. I think that the approximation that relative intensity measured from the scope can be used in place of the log rel..." | Read more » | about 8 years ago | |||
| ygzstc | "Yes the Beer-Lambert Law is based on -log(I/Io) but it's applicable for a single wavelength value. (https://en.wikipedia.org/wiki/Beer%E2%80%93Lamb..." | Read more » | about 8 years ago | |||
| warren | "It's odd -- I see the graphs. Straylight, can you contact web@publiclab.org so we can figure out what's going on there? " | Read more » | about 8 years ago | |||
| straylight | "Thanks for the question. My apologies that all of the graphs appear to have vanished (they have for me). Not sure why, maybe a hosting issue. Anyw..." | Read more » | about 8 years ago | |||
| anjohn12 | "Quick question, I'm trying to do something similar for a school project. Shouldn't the absorbance of the sample be the negative log of the percent ..." | Read more » | about 8 years ago | |||
| msysinfo | "I need to measure oil concentration in a water mixture. Can a SPECTROMETER be used to measure the oil concentration? If it a solute that dissolves ..." | Read more » | over 8 years ago | |||
| straylight | "Good points and I understand how you feel, coming at his from a chemistry teachers viewpoint myself. I guess it depends on what experiments and dem..." | Read more » | about 9 years ago | |||
| srpratt | "I'm new to the cellphone-becomes-a-photospec phenomenon, as I was told about this by a colleague. As an AP Chem teacher, I'm looking for hacks to ..." | Read more » | about 9 years ago | |||
| ichinarayan | "ok thanks so much " | Read more » | over 9 years ago | |||
| straylight | "In spectral workbench, when you are looking at a spectra, there is an option to export and save the data in a variety of formats, including xml and..." | Read more » | over 9 years ago | |||
| ichinarayan | "wow beyond belief. i thought it was complicated listing program. and how do you exported the spectra image into csv form? thanks a lot " | Read more » | over 9 years ago | |||
| straylight | "Thanks for the question ichinarayan, I exported the spectra in csv form into microsoft excel. From there I selected the wavelengths I wanted to st..." | Read more » | over 9 years ago | |||
| ichinarayan | "what software do you use for your analisis program used to generated graph? " | Read more » | over 9 years ago |