Fluorescence Lifetime Measurements and Pulsed Excitation
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Questions and Answers

Which property of light is the most important in bioanalysis?

  • Frequency
  • Intensity
  • Speed
  • Wavelength (correct)

    • What is the speed of light in a vacuum?

  • 3 x 10^12 m/s
  • 3 x 10^10 m/s
  • 3 x 10^6 m/s
  • 3 x 10^8 m/s (correct)

    • What happens when a molecule absorbs light?

  • It scatters light
  • It transitions from a ground state to an excited state (correct)
  • It reflects light
  • It emits light

    • Which of the following is a major application of fluorescence spectroscopy in biology, as mentioned in the text?

    <p>Tracking tagged molecules in complex environments</p> Signup and view all the answers

    What is a limitation of conventional fluorescence microscopes, as mentioned in the text?

    <p>Issues with taking images of thick specimens</p> Signup and view all the answers

    Which of the following is a variant of GFP mentioned in the text?

    <p>CFP</p> Signup and view all the answers

    Which of the following excitation light sources is commonly used in fluorescence microscopes?

    <p>High power light-emitting diode (LED)</p> Signup and view all the answers

    Which type of semiconductor has an excess of electrons or negative charge carriers?

    <p>n-type semiconductor</p> Signup and view all the answers

    What are the three phenomena that occur at a p-n junction?

    <p>Diffusion, formation of space charge, drift</p> Signup and view all the answers

    What is the main function of a diode?

    <p>To control the flow of electricity</p> Signup and view all the answers

    Which process occurs within nanoseconds in fluorescence lifetime measurements?

    <p>Photo saturation</p> Signup and view all the answers

    Which process is responsible for the emission of light by a substance that has absorbed light or other electromagnetic radiation?

    <p>Fluorescence</p> Signup and view all the answers

    What is the main limitation of measuring with stronger excitation light intensities in fluorescence lifetime measurements?

    <p>Photo bleaching</p> Signup and view all the answers

    What is the main difference between fluorescence and phosphorescence?

    <p>Phosphorescent materials emit light for a longer time than fluorescent materials</p> Signup and view all the answers

    What is a fluorochrome?

    <p>A chemical that emits light when exposed to UV radiation</p> Signup and view all the answers

    What is the rate of energy transfer (ket) in Förster resonance energy transfer (FRET) given by?

    <p>td</p> Signup and view all the answers

    What is the energy difference between the absorbed photon and the emitted photon called?

    <p>Stokes shift</p> Signup and view all the answers

    What is the efficiency of the energy transfer (E) in FRET experiments?

    <p>E</p> Signup and view all the answers

    According to the Beer-Lambert law, the extinction coefficient is specific to a molecular species at a given wavelength. Which of the following units is often used to express the extinction coefficient?

    <p>mol L^-1 cm^-1</p> Signup and view all the answers

    To determine the protein contamination in a DNA solution, the absorbance at 260 nm is compared to the absorbance at 280 nm. What ratio indicates the presence of proteins?

    <p>A260/A280 &lt; 1.8</p> Signup and view all the answers

    What is the concentration of double stranded DNA if the absorbance at 260 nm is 0.4 and the extinction coefficient is 0.020 L mg^-1 cm^-1?

    <p>2 mg cm^-3</p> Signup and view all the answers

    What is the concentration of single stranded DNA if the absorbance at 260 nm is 0.3 and the extinction coefficient is 0.027 L mg^-1 cm^-1?

    <p>0.03 mg cm^-3</p> Signup and view all the answers

    Which of the following is true about forward bias in a p-n junction?

    <p>The p-type is connected with the positive terminal of the power supply and the n-type is connected with the negative terminal.</p> Signup and view all the answers

    Which of the following is true about reverse bias in a p-n junction?

    <p>The p-type is connected with the negative terminal of the power supply and the n-type is connected with the positive terminal.</p> Signup and view all the answers

    Which of the following is true about a photodiode?

    <p>It is a variant of a p-n junction.</p> Signup and view all the answers

    Which of the following is true about a photomultiplier tube (PMT)?

    <p>It multiplies the current produced by incident light by as much as 100 million times.</p> Signup and view all the answers

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