Instrumental Analysis - Chapter 15 questions with
verified answers
a singlet or triplet state is formed when Ans✓✓✓ one pair of electrons
of a molecule is excited to a higher energy level
average rate of a triplet-to-singlet transition is less than Ans✓✓✓ that
of a corresponding singlet to singlet transition
Chemiluminescence Ans✓✓✓ based on the emission of radiation by an
excited species formed during a chemical reaction
Chemiluminescence facts Ans✓✓✓ application to analytical chemistry
is recent development, small number of chemical rxns that produce is
produced when a chemical rxn yields electronically excited species that
emits light as it returns to ground state
encountered in a number of biological systems, terms bioluminescence
compounds containing what may also exhibit fluorescence Ans✓✓✓
aliphatic and alicyclic carbonyl structure, or highly conjugated double-
bond structure..... number of these is smaller than the number in the
aromatic systems
, doublet state Ans✓✓✓ ground state for a free radical
two possible orientations for the odd electron in a magnetic field, each
imparts slightly diff energies to the system
dynamic quenching Ans✓✓✓ refers to non-radiative energy transfer
from an excited species to other molecules
also called collisional quenching
requires contact between the excited species and the quenching agent
occurs are rapids as the collision partners can diffuse together, rate is
temp and viscosity dependent
quencher concentration must be high so there is high probability of a
collision during lifetime of excited state
energy level diagrams for photoluminescent molecules Ans✓✓✓ -
jablonski diagram: for typical photoluminescent molecule
-lowest heavy horizontal line represents ground state energy of the
molecules (singlet state: So)
-at room temp ground state represents the energies of most of the
molecules in a solution
verified answers
a singlet or triplet state is formed when Ans✓✓✓ one pair of electrons
of a molecule is excited to a higher energy level
average rate of a triplet-to-singlet transition is less than Ans✓✓✓ that
of a corresponding singlet to singlet transition
Chemiluminescence Ans✓✓✓ based on the emission of radiation by an
excited species formed during a chemical reaction
Chemiluminescence facts Ans✓✓✓ application to analytical chemistry
is recent development, small number of chemical rxns that produce is
produced when a chemical rxn yields electronically excited species that
emits light as it returns to ground state
encountered in a number of biological systems, terms bioluminescence
compounds containing what may also exhibit fluorescence Ans✓✓✓
aliphatic and alicyclic carbonyl structure, or highly conjugated double-
bond structure..... number of these is smaller than the number in the
aromatic systems
, doublet state Ans✓✓✓ ground state for a free radical
two possible orientations for the odd electron in a magnetic field, each
imparts slightly diff energies to the system
dynamic quenching Ans✓✓✓ refers to non-radiative energy transfer
from an excited species to other molecules
also called collisional quenching
requires contact between the excited species and the quenching agent
occurs are rapids as the collision partners can diffuse together, rate is
temp and viscosity dependent
quencher concentration must be high so there is high probability of a
collision during lifetime of excited state
energy level diagrams for photoluminescent molecules Ans✓✓✓ -
jablonski diagram: for typical photoluminescent molecule
-lowest heavy horizontal line represents ground state energy of the
molecules (singlet state: So)
-at room temp ground state represents the energies of most of the
molecules in a solution
