Chapter 6 Flashcards

1
Q

Define coherent radiation C r i r t i m u o w t h i f o s o f a p r t a c w t.

A

C r i r t i m u o w t h i f o s o f a p r t a c w t. Coherent radiation is radiation that is made up of wave trains having identical frequencies or sets of frequencies and phase relationships that are constant with time.

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2
Q

Define dispersion of a transparent substance D i a t m i i v i r i a a f o w.

A

D i a t m i i v i r i a a f o w. Dispersion in a transparent medium is its variation in refractive index as a function of wavelength.

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3
Q

Define anomalous dispersion A d i t s c i r i o a s i a w r w a i o.

A

A d i t s c i r i o a s i a w r w a i o. Anomalous dispersion is the sharp change in refractive index of a substance in a wavelength region where absorption is occurring.

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4
Q

Define work function of a substance T w f o a s i a c t m t e r t r a e f t s o t s.

A

T w f o a s i a c t m t e r t r a e f t s o t s. The work function of a substance is a constant that measures the energy required to remove an electron from the surface of the substance.

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5
Q

Define photoelectric effect T p e i t e o e f t s o a s b a b a b o r.

A

T p e i t e o e f t s o a s b a b a b o r. The photoelectric effect involves the emission of electrons from the surface of a substance brought about by a beam of radiation.

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6
Q

Define ground state of a molecule T g s o a m i i l e s.

A

T g s o a m i i l e s. The ground state of a molecule is its lowest energy state.

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7
Q

Define electronic excitation E e i t p b w e i a s a p f t g s t h e s b a o e.

A

E e i t p b w e i a s a p f t g s t h e s b a o e. Electronic excitation is the process by which electrons in a substance are promoted from their ground state to higher electronic states by absorption of energy.

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8
Q

Define blackbody radiation

B r i t c r e b a s w i i h.

A

B r i t c r e b a s w i i h. Blackbody radiation is the continuum radiation emitted by a solid when it is heated.

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9
Q

Define fluorescence F i a t o e w i b a b i a, i, o m w e r. F i a s-t-s t. T l o t e s i f i v s.

A

F i a t o e w i b a b i a, i, o m w e r. F i a s-t-s t. T l o t e s i f i v s. Fluorescence is a type of emission which is brought about by irradiating atoms, ions, or molecules with electromagnetic radiation. Fluorescence involves a singlet-to-singlet transition. The lifetime of the excited state in fluorescence is very short.

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10
Q

Define phosphorescence

P i a t o e b a b i a m s w e r. P i a t-t-s t a t e s l i l t t o a f s.

A

P i a t o e b a b i a m s w e r. P i a t-t-s t a t e s l i l t t o a f s.

Phosphorescence is a type of emission brought about by irradiating a molecular system with electromagnetic radiation. Phosphorescence involves a triplet-to-singlet transition and the excited state lifetime is longer than that of a fluorescing species.

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11
Q

Define resonance fluorescence R f i a t o e i w t r p i o t s w u t e t f.

A

R f i a t o e i w t r p i o t s w a t u t e t f. Resonance fluorescence is a type of emission in which the radiation produced is of the same wavelength used to excite the fluorescence.

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12
Q

Define photon A p i a b o p o r e w a m o hν, w h i P’s c a ν i t f o t r.

A

A p i a b o p o r e w a m o hν, w h i P’s c a ν i t f o t r. A photon is a bundle or particle of radiant energy with a magnitude of hν, where h is Planck’s constant and ν is the frequency of the radiation.

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13
Q

Define absorptivity A a i d b t e a = A/b, w A i t a o a m c i a c l o b a c c. T p l b i e i c o a s u o l. T c i e i u s a g/L.

A

A, a, i d b t e a = A/b, w A i t a o a m c i a c l o b a c c. T p l b i e i c o a s u o l. T c i e i u s a g/L. Absorptivity a is defined by the equation a = A/bc, where A is the absorbance of a medium contained in a cell length of b and concentration c. The path length b is expressed in cm or another specifice unit of length. The concentration is expressed in units such as g/L.

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14
Q

Define wavenumber T w o r i t r o t w i c.

A

T w o r i t r o t w i c. The wavenumber of radiation is the reciprocal of the wavelength in centimeters.

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15
Q

Define relaxation R i a p w a e s l e a r t a l e s.

A

R i a p w a e s l e a r t a l e s. Relaxation is a process whereby an excited species loses energy and returns to a lower energy state.

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16
Q

Define Stokes shift T S s i t d i w b t i r a t w o f o s.

A

T S s i t d i w b t i r a t w o f o s. The Stokes shift is the difference in wavelength between the incident radiation and the wavelength of fluorescence or scattering.

17
Q

Calculate the frequency in hertz, the energy in joules, and the energy in electron volts of an X-ray photon with a wavelength of 6.24 A.

A
18
Q

The silver iodide bond energy is approximately 255 kllmol (AgI is one of the possible active components in photogray sunglasses). What is the longest wavelength of light that is capable of breaking the bond in silver iodide?

A
19
Q

Calculate the reflection loss when a beam of radiant energy passes through an empty quartz cell assuming the refractive index of quartz is 1.55.

A
20
Q

Explain why the wave model for radiation cannot account for the photoelectric effect.

T w m o r r t t r f a b b e d o a s i s. U t c, n s e c g s e r e t b e f t s a t p a i c.

A

T w m o r r t t r f a b b e d o a s i s. U t c, n s e c g s e r e t b e f t s a t p a i c.

The wave model of radiation requires that the radiation from a beam be evenly distributed over any surface it strikes. Under these circumstances, no single electron could gain sufficient energy rapidly enough to be ejected from the surface and thus provide an
instantaneous current.

21
Q

Convert the following absorbance data into percent transmittance:

(a) 0.278 (b) 1.499 (c) 0039

A

(a) T= antilog (–0.278) = 0.527 or 52.7%.

Similarly, (b) 3.17%, and

(c) 91.4%

22
Q

Convert the following percent transmittance data into absorbance:

(a) 29.9
(b) 86.1
(c) 2.97

A

(a) A= –log(29.9/100) = 0.524.

Similarly (b) 0.065, and

(c) 1.53

23
Q

A solution that was 3.78 X 10-3 M in X had a transmittance of 0.212 when measured in a 2.00-cm cell. What concentration of X would be required for the transmittance to be increased by a factor of 3 when a 1.00-cm cell was used?

A
24
Q

A compound had a molar absorptivity of 3.03 x 103 Lcm-1mol-1. What concentration of the compound would be required to produce a solution that has a transmittance of 9.53% in a 2.50-cm cell?

A