Photoexcitation of anthracene generates the spin triplet = (1 excited state. The X-band EPR (9.50GHz) spectrum from a frozen solution at 77K is shown below. The spectrum can be downloaded for analysis as a text file (q4_anthracene_ triplet.txt) containing field:intensity data that can be plotted in any standard software. (i) With the aid of a suitable energy level diagram, explain how many fully - allowed EPR transitions should be observed for each orientation of the molecule with respect to the applied magnetic field. [2 marks] (ii) Identify the z transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume g = g. ). [2 marks] (iii) Identify the x transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume g=g). [2 marks] (iv) Identify the y transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume g = g). [2 marks] (v) Determine the axial (IDI) and rhombic (IEI) zero - field splitting parameters for the triplet state (MHz units). [2 marks] (vi) Determine the rhombicity parameter -) for the triplet state. [1 mark] (vii) A similar experiment on benzene gives |D| = 4.7GHz and [E] = 600MHz. Explain the difference in the magnitude of IDI between anthracene and benzene. [2 marks]
Photoexcitation of anthracene generates the spin triplet = (1 excited state. The X-band EPR (9.50GHz) spectrum from a frozen solution at 77K is shown below. The spectrum can be downloaded for analysis as a text file (q4_anthracene_ triplet.txt) containing field:intensity data that can be plotted in any standard software. (i) With the aid of a suitable energy level diagram, explain how many fully - allowed EPR transitions should be observed for each orientation of the molecule with respect to the applied magnetic field. [2 marks] (ii) Identify the z transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume g = g. ). [2 marks] (iii) Identify the x transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume g=g). [2 marks] (iv) Identify the y transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume g = g). [2 marks] (v) Determine the axial (IDI) and rhombic (IEI) zero - field splitting parameters for the triplet state (MHz units). [2 marks] (vi) Determine the rhombicity parameter -) for the triplet state. [1 mark] (vii) A similar experiment on benzene gives |D| = 4.7GHz and [E] = 600MHz. Explain the difference in the magnitude of IDI between anthracene and benzene. [2 marks]
Chapter26: Molecular Absorption Spectrometry
Section: Chapter Questions
Problem 26.32QAP
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![Photoexcitation of anthracene generates the spin triplet = (1 excited state. The X-band EPR (9.50GHz) spectrum from
a frozen solution at 77K is shown below. The spectrum can be downloaded for analysis as a text file (q4_anthracene_
triplet.txt) containing field:intensity data that can be plotted in any standard software. (i) With the aid of a suitable
energy level diagram, explain how many fully - allowed EPR transitions should be observed for each orientation of the
molecule with respect to the applied magnetic field. [2 marks] (ii) Identify the z transitions from the spectrum, and give
the separation between them in magnetic field units (mT) and in MHz (assume g = g. ). [2 marks] (iii) Identify the x
transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume
g=g). [2 marks] (iv) Identify the y transitions from the spectrum, and give the separation between them in magnetic
field units (mT) and in MHz (assume g = g). [2 marks] (v) Determine the axial (IDI) and rhombic (IEI) zero - field
splitting parameters for the triplet state (MHz units). [2 marks] (vi) Determine the rhombicity parameter -) for the
triplet state. [1 mark] (vii) A similar experiment on benzene gives |D| = 4.7GHz and [E] = 600MHz. Explain the difference
in the magnitude of IDI between anthracene and benzene. [2 marks]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fdd292f60-9647-4734-a49d-ad264e985b1e%2F992b3137-e55f-4995-a8c9-b80ed62cc691%2Fdoaek4_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Photoexcitation of anthracene generates the spin triplet = (1 excited state. The X-band EPR (9.50GHz) spectrum from
a frozen solution at 77K is shown below. The spectrum can be downloaded for analysis as a text file (q4_anthracene_
triplet.txt) containing field:intensity data that can be plotted in any standard software. (i) With the aid of a suitable
energy level diagram, explain how many fully - allowed EPR transitions should be observed for each orientation of the
molecule with respect to the applied magnetic field. [2 marks] (ii) Identify the z transitions from the spectrum, and give
the separation between them in magnetic field units (mT) and in MHz (assume g = g. ). [2 marks] (iii) Identify the x
transitions from the spectrum, and give the separation between them in magnetic field units (mT) and in MHz (assume
g=g). [2 marks] (iv) Identify the y transitions from the spectrum, and give the separation between them in magnetic
field units (mT) and in MHz (assume g = g). [2 marks] (v) Determine the axial (IDI) and rhombic (IEI) zero - field
splitting parameters for the triplet state (MHz units). [2 marks] (vi) Determine the rhombicity parameter -) for the
triplet state. [1 mark] (vii) A similar experiment on benzene gives |D| = 4.7GHz and [E] = 600MHz. Explain the difference
in the magnitude of IDI between anthracene and benzene. [2 marks]
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