Part A shows how limited the range of the Spectronic 20 spectrometer is. It did not measure

Pennies before 1983 were made with pure copper, while pennies minted after 1983 have a zinc core and a copper shell. The difference between the two types of pennies is the reason why we have to use a penny minted after 1983 for this experiment. Also, a Spec 20 spectroscopic measures the intensity of a light beam after the light beam goes through a sample. The spectrophotometer will compare many samples with one another, and report the percent transmittance and absorbance.

From this graph and chart we can see that the higher the concentration the higher the absorbance, all the different concentrations were tested at the same wavelength (625nm). Also we can determine our unknown substances concentration by using the absorbance we got for it. The red dot on the graph followed by the line towards the horizontal axis indicates that the concentration of fast green was 34% or 5.1x10-3.

The ending result of this experiment confirms that as five test tubes are lined up with the varying level of absorbance, different results in the level of absorbance will appear as well, this is visible in above table. Thus, this is due to the varying amount of water in the solution. The blank sample had a 0.30 in its level of absorbance.

The dark, navy blue colored graph represented the absorbance curve for the S1 sample. The red colored graph represented the absorbance curve for the S2 sample. The green colored graph represented the absorbance curve for the P1 sample. The purple colored graph represented the absorbance curve for the P2 sample. The gaps between the P2 curve was due to the oversaturation that led to the inconclusive spectrophotometer readings. The blue colored graph represented the absorbance curve for the P1 low salt sample. The orange colored graph represented the absorbance curve for the P2 low salt sample. The light blue colored graph represented the absorbance curve for the P1 medium salt sample. The light pink colored graph represented the absorbance curve for the P2 medium salt sample. The light green colored graph represented the absorbance curve for the P1 high salt sample. The light purple colored graph represented the absorbance curve for the P2 high salt

5. The degree of precision was to 3 significant figures obtained with the spectrophotometer. The major source of error in our experiment was not calibrating the spectrophotometer with distilled water.

Grass and Soil have a moderately high reflectance they absorb about 65% and reflect about 35%. The spectral reflectance for the grass and soil typically increases when the wavelength increases, then it stays relatively constant and it increases again.

The validation analysis was made at AERONET WAVECIS (CSI-6) site, since that is the only ocean color site in the Gulf of Mexico. As AERONET station is located to the south of Terrebonne bay and close to the Mississippi River delta, we assumed that it should represent turbid water environment, at least during the Mississippi River flood condition. 19 clear sky Landsat images (100% clear sky image with no sun glint) are acquired over the AERONET station between 2011 and 2014. They included 5 Landsat-5 TM images, 8 Landsat-7 ETM+ images and 6 Landsat-8 OLI images. There are two ways to evaluate the validity of FLAASH corrected satellite observations, 1) by comparing Aerosol optical thickness (AOT) or horizontal visibility and 2) by relating surface reflectance (ρ) or water leaving radiance (Lw). In processing, Aerosol optical thickness (AOT) was obtained first just before & after the satellite overpass time and averaged to keep comparison closer to satellite measurement. MODTRAN4 code in ENVI-FLAASH is not freely available and therefore Although MODTRAN4 code in ENVI-FLAASH calculates AOT (550 nm) using image data and historical climatology, it does not provide AOT as an output product. However, FLAASH do provide horizontal visibility which can be approximately

3. The spectrophotometer was set at 420nm. Distilled water was also used as the ‘blank’.

The results in Graphs and Tables 7 and 8 show that as the wavelength increases the percent transmittance as the absorption decreases. Graph 8 looks cleaner compared to Graph 7 which could be a human error when measuring and diluting the solutions or a potential error with the Spec 20 not reading it

In the study of the spectral range of 400-200 nm devices are used built on the same optical scheme as those for studying the visible range of the spectrum, the difference is only in the glass prisms, lenses, and other optical components. When measuring the intensity of UV emission, as a reference is used source in the UV region of the spectrum with known distribution of the spectral brightness (band tungsten lamp, coal arc, and synchrotron radiation). A thermocouple and graded solar cells are standard receivers in this region of the spectrum. Continue reading →

Lab: Purpose: The purpose of this lab is to use a spectroscope and a light source to determine the how much energy is being emitted from the glass tube. Background: A spectroscope is an instrument which is an instrument used to break up light particles into various wavelengths. The different light sources may include LED, incandescent, fluorescent, gas discharge, and natural light which includes the sun.

The most prominent factor was the spectrophotometer machine itself. The dials were extremely touch sensitive and the values inputted would change even when the dials were not touched and moved. Also, when we would try and turn the dial to increase or decrease the value, miniscule turns of the dial would on occasion result in the value going the other direction, resulting in an even more impossible task of getting the number exactly right. The fact that the settings would change even no one was touching the dials themselves indicates that when we were measuring the absorbance levels of the different pigments, the settings most likely did change and affect the data. We noticed that when the transmittance was off of 100 by 0.2 or 0.4, the absorbance number when nothing was in the spectrophotometer would be positive or negative 0.001, indicating that our data is probably off by only 0.001 if the transmittance only changed by 0.2 or 0.4.

concentration, record the absorbance readings at a fixed wavelength, and plot the absorbance vs. concentration data. The wavelength of 520 nm was selected for experiment Part

Colored dissolved organic matter (CDOM) is an optically active component of total dissolved organic matter (DOM), absorbing light strongly in the UV and visible spectral range, hence influencing light availability in the aquatic environments [1]. Although CDOM protects marine biota from the harmful effects of UV radiation in surface waters [2], it can also adversely affect primary production and the ecosystem health by reducing the quality and the amount of photosynthetically active radiation (PAR) to phytoplankton [3,4]. In estuarine environments, CDOM is primarily of terrestrial origin and is characterized by the presence of humic acid produced by bacterial decomposition of plant litter, animals and organically rich soils [5], whereas in-situ production of CDOM by bacterial and viral decomposition, excretion, grazing, and primary production dominates in oceanic waters [6-9]. Coastal bays are important transition zones between marine and terrigenous environments supplying elevated amounts of sediments, dissolved organic matter, and nutrients to the coastal waters, making them optically complex and challenging for ocean color remote sensing applications. For example, previous studies [8,10-12] have attributed errors in satellite-based estimates of chlorophyll-a to elevated levels of CDOM in coastal waters.

We have timed each of the three experiments for 5 minutes to make sure that our results are correct. Thanks to the program, we got the transmittance and the absorbance, together with the graph portraying our results.