Abstract

The photoelectric yields of small silicate and graphite grains are calculated as a function of incident photon wavelength for the purpose of modeling interstellar grains. The large surface-to-volume ratio of a small grain is expected to result in an increased photoelectric yield when compared with a bulk sample of the same material. The ratio of grain yield to bulk yield is calculated from the Mie solution for the fields inside a spherical particle and from assumptions regarding the electron emission process. Absolute photoelectron yields are calculated from published bulk yields for wavelengths of 900–1500 Å. Results are presented for grain radii of 100 and 1000 Å. These results should be useful for future investigations of photoelectric emission from interstellar grains.

© 1995 Optical Society of America

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References

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  1. H. C. van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957).
  2. C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).
  3. J. S. Mathis, W. Rumpl, and K. H. Nordsieck, “The size distribution of interstellar grains,” Astrophys. J. 217, 425–433 (1977).
    [Crossref]
  4. L. B. d’Hendecourt and A. Léger, Astron. Astrophys. 180, L9–L12 (1987).
  5. W. D. Watson, “Heating of interstellar HI clouds by ultraviolet photoelectron emission from grains,” Astrophys. J. 176, 103–110 (1972).
    [Crossref]
  6. B. T. Draine, “Photoelectric heating of the interstellar gas,” Astrophys. J. 36, 595–619 (1978).
    [Crossref]
  7. W. D. Watson, “Photoelectron emission from small spherical particles,” J. Opt. Soc. Am. 63, 164–165 (1973).
    [Crossref]
  8. B. T. Draine and H. M. Lee, “Optical properties of interstellar graphite and silicate grains,” Astrophys. J. 285, 89–108 (1984).
    [Crossref]

1987 (1)

L. B. d’Hendecourt and A. Léger, Astron. Astrophys. 180, L9–L12 (1987).

1984 (1)

B. T. Draine and H. M. Lee, “Optical properties of interstellar graphite and silicate grains,” Astrophys. J. 285, 89–108 (1984).
[Crossref]

1978 (1)

B. T. Draine, “Photoelectric heating of the interstellar gas,” Astrophys. J. 36, 595–619 (1978).
[Crossref]

1977 (1)

J. S. Mathis, W. Rumpl, and K. H. Nordsieck, “The size distribution of interstellar grains,” Astrophys. J. 217, 425–433 (1977).
[Crossref]

1973 (1)

1972 (1)

W. D. Watson, “Heating of interstellar HI clouds by ultraviolet photoelectron emission from grains,” Astrophys. J. 176, 103–110 (1972).
[Crossref]

Bohren, C. F.

C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).

d’Hendecourt, L. B.

L. B. d’Hendecourt and A. Léger, Astron. Astrophys. 180, L9–L12 (1987).

Draine, B. T.

B. T. Draine and H. M. Lee, “Optical properties of interstellar graphite and silicate grains,” Astrophys. J. 285, 89–108 (1984).
[Crossref]

B. T. Draine, “Photoelectric heating of the interstellar gas,” Astrophys. J. 36, 595–619 (1978).
[Crossref]

Huffman, D. R.

C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).

Lee, H. M.

B. T. Draine and H. M. Lee, “Optical properties of interstellar graphite and silicate grains,” Astrophys. J. 285, 89–108 (1984).
[Crossref]

Léger, A.

L. B. d’Hendecourt and A. Léger, Astron. Astrophys. 180, L9–L12 (1987).

Mathis, J. S.

J. S. Mathis, W. Rumpl, and K. H. Nordsieck, “The size distribution of interstellar grains,” Astrophys. J. 217, 425–433 (1977).
[Crossref]

Nordsieck, K. H.

J. S. Mathis, W. Rumpl, and K. H. Nordsieck, “The size distribution of interstellar grains,” Astrophys. J. 217, 425–433 (1977).
[Crossref]

Rumpl, W.

J. S. Mathis, W. Rumpl, and K. H. Nordsieck, “The size distribution of interstellar grains,” Astrophys. J. 217, 425–433 (1977).
[Crossref]

van de Hulst, H. C.

H. C. van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957).

Watson, W. D.

W. D. Watson, “Photoelectron emission from small spherical particles,” J. Opt. Soc. Am. 63, 164–165 (1973).
[Crossref]

W. D. Watson, “Heating of interstellar HI clouds by ultraviolet photoelectron emission from grains,” Astrophys. J. 176, 103–110 (1972).
[Crossref]

Astron. Astrophys. (1)

L. B. d’Hendecourt and A. Léger, Astron. Astrophys. 180, L9–L12 (1987).

Astrophys. J. (4)

W. D. Watson, “Heating of interstellar HI clouds by ultraviolet photoelectron emission from grains,” Astrophys. J. 176, 103–110 (1972).
[Crossref]

B. T. Draine, “Photoelectric heating of the interstellar gas,” Astrophys. J. 36, 595–619 (1978).
[Crossref]

B. T. Draine and H. M. Lee, “Optical properties of interstellar graphite and silicate grains,” Astrophys. J. 285, 89–108 (1984).
[Crossref]

J. S. Mathis, W. Rumpl, and K. H. Nordsieck, “The size distribution of interstellar grains,” Astrophys. J. 217, 425–433 (1977).
[Crossref]

J. Opt. Soc. Am. (1)

Other (2)

H. C. van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957).

C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).

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Figures (4)

Fig. 1
Fig. 1

Yield enhancement Ea (thick curve) and complex index of refraction m (thin curves) for silicate grains of radius 1000 Å as a function of incident photon wavelength.

Fig. 2
Fig. 2

Yield enhancement Ea (thick curve) and complex index of refraction m (thin curves) for graphite grains of radius 100 Å as a function of incident photon wavelength. The enhancements for parallel and perpendicular polarizations have been averaged (see text). The indices of refraction have also been averaged for ease of presentation.

Fig. 3
Fig. 3

Yield enhancement Ea (thick curve) and complex index of refraction m (thin curves) for graphite grains of radius 1000 Å as a function of incident photon wavelength. The enhancements for parallel and perpendicular polarizations have been averaged (see text). The indices of refraction have also been averaged for ease of presentation.

Fig. 4
Fig. 4

Absolute photoelectric yields Ya as a function of incident photon wavelength for silicate (thin curves) and graphite (thick curves) grains with radii of 100 Å (upper curve) and 1000 Å (lower curve).

Equations (20)

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n ( a ) a - 3.5             ( 50 Å a 2500 Å ) ,
P e = C exp [ - ( a - r ) / L e ] ,
Y a = V ( · S ) C exp [ - ( a - r ) / L e ] d V V ( · S ) d V .
L a = λ 4 π Im ( m ) .
Y b = C L e ( L e + L a ) .
F ( r ) = 1 4 π 0 4 π ( · S ) d Ω ,
E a = ( L e + L a ) 0 a exp [ - ( a - r ) / L e ] 4 π r 2 F ( r ) d r L e 0 a 4 π r 2 F ( r ) d r .
Y a = E a Y b .
h n ( 1 ) ( ρ ) = j n ( ρ ) + i y n ( ρ ) ,
ψ n ( ρ ) = ρ j n ( ρ ) , ξ n ( ρ ) = ρ h n ( 1 ) ( ρ ) ,
F ( r ) = 1 k 2 r 2 n = 1 ( 2 n + 1 ) × { c n 2 [ ψ n ( z ) 2 + n ( n + 1 ) ψ n ( z ) 2 z 2 ] + d n 2 ψ n ( z ) 2 } ,
c n = j n ( x ) [ x h n ( 1 ) ( x ) ] - h n ( 1 ) ( x ) [ x j n ( x ) ] j n ( m x ) [ x h n ( 1 ) ( x ) ] - h n ( 1 ) ( x ) [ m x j n ( m x ) ] ,
d n = m j n ( x ) [ x h n ( 1 ) ( x ) ] - m h n ( 1 ) ( x ) [ x j n ( x ) ] m 2 j n ( m x ) [ x h n ( 1 ) ( x ) ] - h n ( 1 ) ( x ) [ m x j n ( m x ) ] .
D n ( x ) = ψ n ( x ) ψ n ( x ) .
D n - 1 ( x ) = n x - 1 D n ( x ) + n / x ,
c n = i ψ n ( m x ) { [ m D n ( m x ) + n x ] ξ n ( x ) - ξ n - 1 ( x ) } ,
d n = i ψ n ( m x ) { [ D n ( m x ) m + n x ] ξ n ( x ) - ξ n - 1 ( x ) } ,
ψ n ( x ) = ψ n - 1 ( x ) - n ψ n ( x ) x ,
ξ n ( x ) = ξ n - 1 ( x ) - n ξ n ( x ) x .
F ( r ) = 1 k 2 r 2 n = 1 ( 2 n + 1 ) ψ n ( z ) 2 × { c n 2 [ D n ( z ) 2 + n ( n + 1 ) z 2 ] + d n 2 } .

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