Abstract

An infrared–microwave double-resonance technique using microwave sidebands of CO2 laser lines as an infrared source has been applied for observation of rotational lines of the methanol molecule. Frequencies of more than 50 rotational lines in the excited CO stretching vibrational state (vco=1) have been measured with good precision and have been compared with those reported in infrared studies. Many of them agree within several megahertz, although some lines show differences of >10 MHz. The pressure dependence of the double-resonance signals for two low-J microwave transitions belonging to the ground and the vco=1 states, respectively, have been observed for sample pressures as high as 0.4 Torr. For the former transition the signal has been observed to change its sign at higher pressures. Rate equation analysis explains the observed pressure dependence quantitatively and allows us to understand the physical processes involved in the double resonance.

© 1999 Optical Society of America

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References

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  1. F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
    [CrossRef]
  2. C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
    [CrossRef]
  3. L. H. Xu, A. M. Andrews, and G. T. Fraser, “Study of the overtone ĆO stretching band of methanol by multiple resonance spectroscopy,” J. Chem. Phys. 103, 14–19 (1995).
    [CrossRef]
  4. R. M. Lees, “Torsion–vibration interactions in methanol. IV. Microwave spectrum of CH3OH in the excited CO stretching state,” J. Chem. Phys. 57, 2249–2252 (1972).
    [CrossRef]
  5. S. Tsunekawa, T. Ukai, A. Toyama, and K. Takagi, Department of Physics, Toyama University, Toyama 930-8555, Japan (personal communication, 1995).
  6. I. Mukhopadhyay, R. M. Lees, and K. V. L. N. Sastry, “Detection of weak microwave and millimeter wave transitions in the C—O stretch of methyl alcohol,” Infrared Phys. 30, 291–293 (1990).
    [CrossRef]
  7. G. Moruzzi, B. P. Winnewisser, M. Winnewisser, I. Mukhopadhyay, and F. Strumia, Microwave, Infrared and Laser Transitions of Methanol (CRC Press, Boca Raton, Fla., 1995).
  8. K. Shimoda and M. Takami, “Pressure dependence of infrared-microwave double resonance in formaldehyde,” Opt. Commun. 4, 388–391 (1972).
    [CrossRef]
  9. M. Takami and K. Shimoda, “Infrared-microwave double resonance in H2CO with a Zeeman-tuned 3.5μm He–Xe laser,” Jpn. J. Appl. Phys. 11, 1648–1656 (1972).
    [CrossRef]
  10. M. Takami, “Theory of optical-microwave double resonance I. Fundamentals and double resonance of microwave detection,” Jpn. J. Appl. Phys. 15, 1063–1071 (1976).
    [CrossRef]
  11. M. Takami, “Theory of optical-microwave double resonance II. Double resonance with optical detection,” Jpn. J. Appl. Phys. 15, 1889–1897 (1976).
    [CrossRef]
  12. P. K. Cheo, “Frequency synthesized and continuously tunable IR laser sources in 9–11 μm,” IEEE J. Quantum Electron. QE-20, 700–709 (1984).
    [CrossRef]
  13. P. K. Cheo, Z. Chu, and Y. Zhou, “Applications of a tunable CO2 sideband laser for high-resolution spectroscopic measurements of atmospheric gases,” Appl. Opt. 32, 836–841 (1993).
    [CrossRef] [PubMed]
  14. M. Dang-Nhu, G. Blanquet, and J. Walrand, “Intensities of methanol spectra around 12.5 μm,” J. Mol. Spectrosc. 146, 524–526 (1991).
    [CrossRef]
  15. M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
    [CrossRef]
  16. T. Oka, “A search for interstellar H3+,” Philos. Trans. R. Soc. London, Ser. A 303, 543–549 (1981).
    [CrossRef]
  17. C. H. Townes and A. L. Schawlow, Microwave Spectroscopy (McGraw-Hill, New York, 1975).
  18. R. M. Lees and S. S. Haque, “Microwave double resonance study of collision induced population transfer between levels of interstellar methanol lines,” Can. J. Phys. 52, 2250–2271 (1974).
  19. M. Takami and K. Shimoda, “Microwave spectrum of the vibrationally excited state of molecules by infrared-microwave double resonance,” Jpn. J. Appl. Phys. 12, 603–604 (1973).
    [CrossRef]
  20. K. V. L. N. Sastry, R. M. Lees, and J. Van der Linde, “Dipole moment of CH3OH,” J. Mol. Spectrosc. 88, 228–230 (1981).
    [CrossRef]

1995 (1)

L. H. Xu, A. M. Andrews, and G. T. Fraser, “Study of the overtone ĆO stretching band of methanol by multiple resonance spectroscopy,” J. Chem. Phys. 103, 14–19 (1995).
[CrossRef]

1994 (1)

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

1993 (1)

1991 (1)

M. Dang-Nhu, G. Blanquet, and J. Walrand, “Intensities of methanol spectra around 12.5 μm,” J. Mol. Spectrosc. 146, 524–526 (1991).
[CrossRef]

1990 (2)

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

I. Mukhopadhyay, R. M. Lees, and K. V. L. N. Sastry, “Detection of weak microwave and millimeter wave transitions in the C—O stretch of methyl alcohol,” Infrared Phys. 30, 291–293 (1990).
[CrossRef]

1984 (2)

F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
[CrossRef]

P. K. Cheo, “Frequency synthesized and continuously tunable IR laser sources in 9–11 μm,” IEEE J. Quantum Electron. QE-20, 700–709 (1984).
[CrossRef]

1981 (2)

K. V. L. N. Sastry, R. M. Lees, and J. Van der Linde, “Dipole moment of CH3OH,” J. Mol. Spectrosc. 88, 228–230 (1981).
[CrossRef]

T. Oka, “A search for interstellar H3+,” Philos. Trans. R. Soc. London, Ser. A 303, 543–549 (1981).
[CrossRef]

1976 (2)

M. Takami, “Theory of optical-microwave double resonance I. Fundamentals and double resonance of microwave detection,” Jpn. J. Appl. Phys. 15, 1063–1071 (1976).
[CrossRef]

M. Takami, “Theory of optical-microwave double resonance II. Double resonance with optical detection,” Jpn. J. Appl. Phys. 15, 1889–1897 (1976).
[CrossRef]

1974 (1)

R. M. Lees and S. S. Haque, “Microwave double resonance study of collision induced population transfer between levels of interstellar methanol lines,” Can. J. Phys. 52, 2250–2271 (1974).

1973 (1)

M. Takami and K. Shimoda, “Microwave spectrum of the vibrationally excited state of molecules by infrared-microwave double resonance,” Jpn. J. Appl. Phys. 12, 603–604 (1973).
[CrossRef]

1972 (3)

K. Shimoda and M. Takami, “Pressure dependence of infrared-microwave double resonance in formaldehyde,” Opt. Commun. 4, 388–391 (1972).
[CrossRef]

M. Takami and K. Shimoda, “Infrared-microwave double resonance in H2CO with a Zeeman-tuned 3.5μm He–Xe laser,” Jpn. J. Appl. Phys. 11, 1648–1656 (1972).
[CrossRef]

R. M. Lees, “Torsion–vibration interactions in methanol. IV. Microwave spectrum of CH3OH in the excited CO stretching state,” J. Chem. Phys. 57, 2249–2252 (1972).
[CrossRef]

Allegrini, M.

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

Andrews, A. M.

L. H. Xu, A. M. Andrews, and G. T. Fraser, “Study of the overtone ĆO stretching band of methanol by multiple resonance spectroscopy,” J. Chem. Phys. 103, 14–19 (1995).
[CrossRef]

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

Blanquet, G.

M. Dang-Nhu, G. Blanquet, and J. Walrand, “Intensities of methanol spectra around 12.5 μm,” J. Mol. Spectrosc. 146, 524–526 (1991).
[CrossRef]

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

Cheo, P. K.

P. K. Cheo, Z. Chu, and Y. Zhou, “Applications of a tunable CO2 sideband laser for high-resolution spectroscopic measurements of atmospheric gases,” Appl. Opt. 32, 836–841 (1993).
[CrossRef] [PubMed]

P. K. Cheo, “Frequency synthesized and continuously tunable IR laser sources in 9–11 μm,” IEEE J. Quantum Electron. QE-20, 700–709 (1984).
[CrossRef]

Chu, Z.

Dang-Nhu, M.

M. Dang-Nhu, G. Blanquet, and J. Walrand, “Intensities of methanol spectra around 12.5 μm,” J. Mol. Spectrosc. 146, 524–526 (1991).
[CrossRef]

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

Fraser, G. T.

L. H. Xu, A. M. Andrews, and G. T. Fraser, “Study of the overtone ĆO stretching band of methanol by multiple resonance spectroscopy,” J. Chem. Phys. 103, 14–19 (1995).
[CrossRef]

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

Frye, J. M.

F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
[CrossRef]

Haque, S. S.

R. M. Lees and S. S. Haque, “Microwave double resonance study of collision induced population transfer between levels of interstellar methanol lines,” Can. J. Phys. 52, 2250–2271 (1974).

Kreiner, W. A.

F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
[CrossRef]

Lees, R. M.

I. Mukhopadhyay, R. M. Lees, and K. V. L. N. Sastry, “Detection of weak microwave and millimeter wave transitions in the C—O stretch of methyl alcohol,” Infrared Phys. 30, 291–293 (1990).
[CrossRef]

K. V. L. N. Sastry, R. M. Lees, and J. Van der Linde, “Dipole moment of CH3OH,” J. Mol. Spectrosc. 88, 228–230 (1981).
[CrossRef]

R. M. Lees and S. S. Haque, “Microwave double resonance study of collision induced population transfer between levels of interstellar methanol lines,” Can. J. Phys. 52, 2250–2271 (1974).

R. M. Lees, “Torsion–vibration interactions in methanol. IV. Microwave spectrum of CH3OH in the excited CO stretching state,” J. Chem. Phys. 57, 2249–2252 (1972).
[CrossRef]

Miller, C. C.

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

Moruzzi, G.

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

Mukhopadhyay, I.

I. Mukhopadhyay, R. M. Lees, and K. V. L. N. Sastry, “Detection of weak microwave and millimeter wave transitions in the C—O stretch of methyl alcohol,” Infrared Phys. 30, 291–293 (1990).
[CrossRef]

Oka, T.

F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
[CrossRef]

T. Oka, “A search for interstellar H3+,” Philos. Trans. R. Soc. London, Ser. A 303, 543–549 (1981).
[CrossRef]

Pate, B. H.

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

Philips, L. A.

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

Sastry, K. V. L. N.

I. Mukhopadhyay, R. M. Lees, and K. V. L. N. Sastry, “Detection of weak microwave and millimeter wave transitions in the C—O stretch of methyl alcohol,” Infrared Phys. 30, 291–293 (1990).
[CrossRef]

K. V. L. N. Sastry, R. M. Lees, and J. Van der Linde, “Dipole moment of CH3OH,” J. Mol. Spectrosc. 88, 228–230 (1981).
[CrossRef]

Scappini, F.

F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
[CrossRef]

Shimoda, K.

M. Takami and K. Shimoda, “Microwave spectrum of the vibrationally excited state of molecules by infrared-microwave double resonance,” Jpn. J. Appl. Phys. 12, 603–604 (1973).
[CrossRef]

K. Shimoda and M. Takami, “Pressure dependence of infrared-microwave double resonance in formaldehyde,” Opt. Commun. 4, 388–391 (1972).
[CrossRef]

M. Takami and K. Shimoda, “Infrared-microwave double resonance in H2CO with a Zeeman-tuned 3.5μm He–Xe laser,” Jpn. J. Appl. Phys. 11, 1648–1656 (1972).
[CrossRef]

Suenram, R. D.

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

Takami, M.

M. Takami, “Theory of optical-microwave double resonance I. Fundamentals and double resonance of microwave detection,” Jpn. J. Appl. Phys. 15, 1063–1071 (1976).
[CrossRef]

M. Takami, “Theory of optical-microwave double resonance II. Double resonance with optical detection,” Jpn. J. Appl. Phys. 15, 1889–1897 (1976).
[CrossRef]

M. Takami and K. Shimoda, “Microwave spectrum of the vibrationally excited state of molecules by infrared-microwave double resonance,” Jpn. J. Appl. Phys. 12, 603–604 (1973).
[CrossRef]

K. Shimoda and M. Takami, “Pressure dependence of infrared-microwave double resonance in formaldehyde,” Opt. Commun. 4, 388–391 (1972).
[CrossRef]

M. Takami and K. Shimoda, “Infrared-microwave double resonance in H2CO with a Zeeman-tuned 3.5μm He–Xe laser,” Jpn. J. Appl. Phys. 11, 1648–1656 (1972).
[CrossRef]

Van der Linde, J.

K. V. L. N. Sastry, R. M. Lees, and J. Van der Linde, “Dipole moment of CH3OH,” J. Mol. Spectrosc. 88, 228–230 (1981).
[CrossRef]

Walrand, J.

M. Dang-Nhu, G. Blanquet, and J. Walrand, “Intensities of methanol spectra around 12.5 μm,” J. Mol. Spectrosc. 146, 524–526 (1991).
[CrossRef]

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

Xu, L. H.

L. H. Xu, A. M. Andrews, and G. T. Fraser, “Study of the overtone ĆO stretching band of methanol by multiple resonance spectroscopy,” J. Chem. Phys. 103, 14–19 (1995).
[CrossRef]

Zhou, Y.

Appl. Opt. (1)

Can. J. Phys. (1)

R. M. Lees and S. S. Haque, “Microwave double resonance study of collision induced population transfer between levels of interstellar methanol lines,” Can. J. Phys. 52, 2250–2271 (1974).

IEEE J. Quantum Electron. (1)

P. K. Cheo, “Frequency synthesized and continuously tunable IR laser sources in 9–11 μm,” IEEE J. Quantum Electron. QE-20, 700–709 (1984).
[CrossRef]

Infrared Phys. (1)

I. Mukhopadhyay, R. M. Lees, and K. V. L. N. Sastry, “Detection of weak microwave and millimeter wave transitions in the C—O stretch of methyl alcohol,” Infrared Phys. 30, 291–293 (1990).
[CrossRef]

J. Chem. Phys. (3)

C. C. Miller, L. A. Philips, A. M. Andrews, G. T. Fraser, B. H. Pate, and R. D. Suenram, “Rotational spectrum of a dark state in 2-fluoroethanol using microwave/radio-frequency-infrared multiple resonance,” J. Chem. Phys. 100, 831–839 (1994).
[CrossRef]

L. H. Xu, A. M. Andrews, and G. T. Fraser, “Study of the overtone ĆO stretching band of methanol by multiple resonance spectroscopy,” J. Chem. Phys. 103, 14–19 (1995).
[CrossRef]

R. M. Lees, “Torsion–vibration interactions in methanol. IV. Microwave spectrum of CH3OH in the excited CO stretching state,” J. Chem. Phys. 57, 2249–2252 (1972).
[CrossRef]

J. Mol. Spectrosc. (4)

F. Scappini, W. A. Kreiner, J. M. Frye, and T. Oka, “Radiofrequency-infrared double resonance spectroscopy of OsO4 using microwave modulation sidebands on CO2 laser lines,” J. Mol. Spectrosc. 106, 436–440 (1984).
[CrossRef]

M. Dang-Nhu, G. Blanquet, and J. Walrand, “Intensities of methanol spectra around 12.5 μm,” J. Mol. Spectrosc. 146, 524–526 (1991).
[CrossRef]

M. Dang-Nhu, G. Blanquet, J. Walrand, M. Allegrini, and G. Moruzzi, “Intensities of the CO stretch band of CH3OH at 9.7 μm,” J. Mol. Spectrosc. 141, 348–350 (1990).
[CrossRef]

K. V. L. N. Sastry, R. M. Lees, and J. Van der Linde, “Dipole moment of CH3OH,” J. Mol. Spectrosc. 88, 228–230 (1981).
[CrossRef]

Jpn. J. Appl. Phys. (4)

M. Takami and K. Shimoda, “Microwave spectrum of the vibrationally excited state of molecules by infrared-microwave double resonance,” Jpn. J. Appl. Phys. 12, 603–604 (1973).
[CrossRef]

M. Takami and K. Shimoda, “Infrared-microwave double resonance in H2CO with a Zeeman-tuned 3.5μm He–Xe laser,” Jpn. J. Appl. Phys. 11, 1648–1656 (1972).
[CrossRef]

M. Takami, “Theory of optical-microwave double resonance I. Fundamentals and double resonance of microwave detection,” Jpn. J. Appl. Phys. 15, 1063–1071 (1976).
[CrossRef]

M. Takami, “Theory of optical-microwave double resonance II. Double resonance with optical detection,” Jpn. J. Appl. Phys. 15, 1889–1897 (1976).
[CrossRef]

Opt. Commun. (1)

K. Shimoda and M. Takami, “Pressure dependence of infrared-microwave double resonance in formaldehyde,” Opt. Commun. 4, 388–391 (1972).
[CrossRef]

Philos. Trans. R. Soc. London, Ser. A (1)

T. Oka, “A search for interstellar H3+,” Philos. Trans. R. Soc. London, Ser. A 303, 543–549 (1981).
[CrossRef]

Other (3)

C. H. Townes and A. L. Schawlow, Microwave Spectroscopy (McGraw-Hill, New York, 1975).

G. Moruzzi, B. P. Winnewisser, M. Winnewisser, I. Mukhopadhyay, and F. Strumia, Microwave, Infrared and Laser Transitions of Methanol (CRC Press, Boca Raton, Fla., 1995).

S. Tsunekawa, T. Ukai, A. Toyama, and K. Takagi, Department of Physics, Toyama University, Toyama 930-8555, Japan (personal communication, 1995).

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Figures (10)

Fig. 1
Fig. 1

Experimental setup for CO2 laser sideband microwave double-resonance spectroscopy. B.S., beam splitter; L1–L3, ZnSe lenses; M1–M3, mirrors; TWTA, traveling-wave tube amplifier; F.P., Fabry–Perot interferometer; PSD, phase-sensitive detector.

Fig. 2
Fig. 2

Recorder tracing of the microwave transition vco=1, vt=0, E, 1120 of CH3OH at 64,199.93 MHz with the infrared transition 20, vco=110, vco=0.

Fig. 3
Fig. 3

Energy levels relevant to the signal shown in Fig. 2.

Fig. 4
Fig. 4

Dependence of the double-resonance signal (scheme 1) on infrared frequency shift from its line center.

Fig. 5
Fig. 5

Histogram of the deviations between observed and predicted frequencies appearing in Tables 1 and 2.

Fig. 6
Fig. 6

Energy level scheme of CH3OH including the microwave transition 102-1 in the ground state for E species and vt=0.

Fig. 7
Fig. 7

Observed dependence of -ln(I/I0) for the vco=1, 20vco=0, 10 transition for E, vt=0 of CH3OH on sample pressure. Deviations from the straight line arise from experimental uncertainties.

Fig. 8
Fig. 8

Observed dependence of -ln(I/I0) for the vco=1, 1-1vco=0, 2-1 transition for E, vt=0 of CH3OH on sample pressure. Deviations from the straight line arise from experimental uncertainties.

Fig. 9
Fig. 9

Observed pressure dependence (filled circles) and calculated pressure dependence (dashed curves) of the double-resonance signal corresponding to the microwave transition 1120 in the vco=1 state of CH3OH (scheme 1) for the input infrared powers of (a) 8.2 and (b) 5.9 mW.

Fig. 10
Fig. 10

Observed pressure dependence (filled circles) and calculated pressure dependence (dashed curves) of the double-resonance signal corresponding to the microwave transition 102-1 in the ground state of CH3OH (scheme 2) for the input infrared powers of (a) 11.3 and (b) 7.8 mW.

Tables (4)

Tables Icon

Table 1 Observed A Symmetry Transitions of CH3OH

Tables Icon

Table 2 Observed E Symmetry Transitions of CH3OH

Tables Icon

Table 3 Observed Values of αg, Sif, and μ(1, 0) for vco=10 in vt=0 of CH3OH

Tables Icon

Table 4 Rabi Frequencies for |M|=1 Determined from the Pressure Dependence of the Double-Resonance Signal

Equations (10)

Equations on this page are rendered with MathJax. Learn more.

Sif=8π33hcνifL T0TεZrZi|μ(1, 0)|2[1-exp(-hνif/kT)]×exp[-hc(E-W0)/kT]A(J, K, J, K).
αg(ν0)=Sifϕ(ν0, T)/760,
ΔP
=πω|x|2kuN10[1-exp(-αpl)]αpl×1-δ2ηη+1(1+3η+44η+4ξ)1/2+1+3η+44η+4ξ exp(-αpl)1/2-1(1+ξ)1/2+[1+ξ exp(-αpl)]1/2.
τc-1=C1p,
τ-1=τc-1+τs-1,
μ=μ(1, 0) [(J+1)2-K2]1/2[(J+1)2-M2]1/2(J+1)[(2J+1)(2J+3)]1/2,
μm=μbIσKσK [(J-K)(J-K-1)]1/2(J2-M2)1/22J(4J2-1)1/2,
ΔP=πωN10|x|24kuηη+1ξ4-δ.
pmin=12C12δ{3x2+4δxm2+[(3x2+4δxm2)2-14δx2xm2]1/2}1/2.

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