1E21཯ᛂ㐣⛬䛾 㻵㼂㻾䠖㻌 ィ⟬ศᏊศගᏛ䛻䛚䛡䜛᪂䛧䛔ྲྀ䜚⤌䜏㻌࠾Ⲕ኱⌮ 1, Waterloo ኱Ꮫ (࢝ࢼࢲ)2‫ۑ‬ᖹ㔝 ᜏኵ 1, Hui Li2, Robert Le Roy 2, ኳᇣሕ⩏ 2ࠕ཯ᛂ㐣⛬ࡢ IVR (Intramolecular Vibrational Energy Redistribution)ࠖ ࡣࠊ࡯࡜ࢇ࡝ᮍ㛤ᣅࡢ㡿ᇦ࡛࠶ࡿࠋ㧗┿✵ୗࡸࣇ࣮ࣜࢪ࢙ࢵࢺ࡛ࡢศගᏛ ᐃࡢሙྜࠊ⏕ᡂ≀ྠኈࡲࡓࡣ⏕ᡂ≀࡜⫼ᬒศᏊ࡜ࡢ⾪✺⦆࿴ࡀᑡ࡞࠸ࡓࡵࠊ཯ᛂ㐣⛬ࡢ IVR ࡛⏕ࡌࡓ≉ู࡞᣺ືບ㉳≧ែࡀほ ࡉࢀࡿࡇ࡜ࡀ࠶
ࡿࠋ౛࠼ࡤࠊH3+ +CO ࠿ࡽ⏕ᡂࡍࡿ HCO+࡛ࡣࠊఙ⦰᣺ືࡢ᣺ື ᗘࡀ㧗ࡃࠊl ࡢ␗࡞ࡿບ㉳ኚゅ᣺ືࡢ㛫࡟⇕ᖹ⾮ࡀᡂ❧ࡋ࡚࡞ࡃࠊࡲࡓ(0220)ࡸ(0420)ࡢ J ࡢప࠸ࢩࢢࢼࣝࡣ emission ࡜ࡋ࡚ほࡉࢀ࡚࠸ࡿࠋa,b ࡇࡢ཯ᛂ࡟ࡘ࠸࡚ࡣࠊ᪤࡟ 5 ḟඖࡢ࣏ࢸࣥࢩ࢚ࣕࣝࢿࣝࢠ࣮᭤㠃 (PES) ࢆィ⟬ࡋ࡚ࠊCO ࡢ C ➃࡬ࡢ H3+ࡢ collinear approach ࡀ୺࡞཯ᛂ⤒㊰࡛࠶ࡿࡇ࡜ࢆሗ࿌ࡋ࡚࠶ࡿࠋc ࡇࡢሙྜࠊ᥋㏆ࡋ࡚ࡃࡿ H3+ศᏊ୰ࡢ H+ࡢ୪㐍㐠ືࡣ⏕ᡂ≀ HCO+ࡢ H-C 㛫ࡢఙ⦰㐠ື࡜ࡶぢ࡞ࡉࢀࡿࡢ࡛ࠊࡲࡎ H-C ఙ⦰᣺ືࡀࠊ⥆࠸࡚ CO ఙ⦰᣺ືࡀບ㉳ࡉࢀࠊࡶࡋ H+ࡀ collinear ࠿ࡽእࢀࡿ㐠ືᡂศࢆࡶࡗ࡚࠸ࢀࡤࠊኚゅ᣺ືࡶ IVR ࢆ㏻ࡋ࡚ບ㉳ࡉࢀࡿࡇ࡜ࡀண᝿ࡉࢀࡿࠋd཯ᛂ㐣⛬ࡢ IVR ࡜ࡋ࡚ࡣࠊᡃࠎࡣ᪤࡟ࠊHNC ! HCN ࡢ␗ᛶ໬཯ᛂ࡟㛵ࡋ࡚ࠊab initio directdynamcs ࡛ồࡵࡓ཯ᛂ⤒㊰࡟㛵ࡋ࡚ࠊvibration mixingࠊvibration mapping ࡢᡭἲ e,f ࢆ㐺⏝ࡋ࡚཯ᛂ
H3+ +CO ! HCO+㐣⛬ࡢ IVR ࡟㛵ࡍࡿゎᯒࢆ⾜ࡗ࡚࠸ࡿࠋg ௒ᅇࡣࠊྠᵝ࡞ᡭἲࢆ᭦࡟Ⓨᒎࡉࡏ࡚ࠊ
཯ᛂ࡟㐺⏝ࡋࡓࠋ
ࡇࡢ཯ᛂࡣࠕ࢖࢜ࣥ-ศᏊࠖ཯ᛂ࡞ࡢ࡛ࠊ඲య࡜ࡋ࡚ࡣ downhill ࡢ཯ᛂ࡛࠶ࡿࡀࠊ5 ḟඖ PES ࡢ◊✲ c ࡟ࡼࢀࡤࠊ㏵୰࡛ H3+…CO ࡜࠸࠺㘒యࢆ⤒⏤ࡍࡿࡇ࡜ࡀศ࠿ࡗ࡚࠸ࡿࡢ࡛ࠊከ㓄⨨࡛㟁Ꮚ┦㛵ࢆ㢳៖ࡋࠊ࠿ࡘゎᯒⓗ࡞ gradient (= !force) ࡀ౑࠼ࡿ RS2 (MOLPRO 2006.1) ࣞ࣋ࣝࡢ ab initio
direct dynamcs ࡛཯ᛂࢆ㏣ࡗࡓࠋ⏝࠸ࡓᇶᗏ㛵ᩘࡣ aug-cc-pVQZ (C, O, H)࡛࠶ࡿࠋ཯ᛂ ᗘࡣࠊᫍ㛫㞼ࡢ඾ᆺⓗ࡞ ᗘ 20 K ࡜ࠊᐊෆᐇ㦂࡛ࡢほ ࠿ࡽồࡵࡓᐇຠ ᗘ 330 K ࡢ 2 ✀㢮ࢆ᝿ᐃࡋࠊ
time-step ࡣ 0.2fs ࡛ࠊᑡ࡞ࡃ࡜ࡶ 1500 steps ࡲ࡛ࠊࡲࡓࡣ㞳ࢀ࡚࠸ࡃ H2 ࡜⏕ᡂࡍࡿ HCO+ࡢ㊥㞳ࡀ
20 Å ࡟࡞ࡿࡲ࡛ࡢ ab initio direct dynamics ࢆ⾜ࡗࡓࠋ Direct dynamics ࡢึᮇ್࡜ࡋ࡚ࠊ4 Å 㞳ࡋ
ࡓ H3+࡜ CO ࠿ࡽᡂࡿ⣔࡟ࠊ㞽Ⅼ᣺ື࢚ࢿࣝࢠ࣮࠾ࡼࡧタᐃ ᗘ࡟┦ᙜࡍࡿ㐠ື࢚ࢿࣝࢠ࣮࡟ᑐᛂ
ࡍࡿ㏿ᗘᡂศࢆࠊ஘ᩘࢆ᣺ࡗ࡚ྛཎᏊ࡟୚࠼ࡓࠋ᫬⣔ิ࡜ࡋ࡚ồࡲࡿྛ step ࡢศᏊ⣔ࡢᵓ㐀࠿ࡽ
HCO+ 㒊ศࡢᗙᶆࢆᢤࡁฟࡋ࡚ࠊ
ࡑࢀࢆ୺㍈⣔ࡢኚ఩ᗙᶆ࡟ኚ᥮ࡋࠊ
ྠࡌࡃ RS2 ࡛ồࡵࡓ HCO+ศᏊࡢᇶ‽᣺ື࡬ mapping ࡋࡓࠋᇶ‽᣺
ືࡣ㉁㔞ᗙᶆ⣔࡛ࡢつ᱁┤஺ᗙᶆ࡜ࡋ࡚᏶඲⣔ࢆ࡞ࡍࡢ࡛ࠊࡇࡢ
mapping ࡣྍ⬟࡛࠶ࡿࠋᚓࡽࢀࡓ
mapping ಀᩘࡢ᫬⣔ิࢹ࣮ࢱࢆࣇ
࣮࢚ࣜኚ᥮ࡋ࡚࿘Ἴᩘᡂศࢆồࡵࡓࠋ
330 K࡛ࡢcollinear approachࡢሙྜࡢࠊsnapshotsࢆᅗ 1 ࡟♧ࡍࠋࡇᅗ㸯 Snapshots, collinear approach at 330K

ࡢsnapshots࠿ࡽศ࠿ࡿࡼ࠺࡟ࠊࡍࢇ࡞ࡾ࡜
downhillࡢ཯ᛂࡀ㐍⾜ࡍࡿࡢ࡛ࡣ࡞ࡃࠊ67 fs
㡭࠿ࡽጞࡲࡿH3+࠿ࡽࡢH+ࡢhoppingࡣࠊ4ᅇࡢ
཯㊴ࢆྵࡵ࡚ࠊ⣙120 fs࡯࡝࠿࠿ࡗ࡚᏶஢ࡋࠊ
HCO+ࡀ⏕ᡂࡋ࡚࠸ࡿࠋࡇࢀࢆ᣺ືࡢ❧ሙ࠿ࡽࡳࡿ࡜ࠊ᭱ึࡣH3+࠿ࡽࡢH+ࡢ᥋㏆࡟ࡘࢀ࡚
CO㒊ศࡢ᣺ືࡀບ㉳ࡉࢀࡿࡀࠊ156 fs࠶ࡓࡾ࠿ࡽኚゅ᣺ືࡀጞࡲࡾࠊH+ࡢ᭱⤊ᅇࡢ᥋㏆ࡢ
ᚋࡣኚゅ᣺ືࡀ㢧ⴭ࡟࡞ࡗ࡚࠸ࡿࠋMappingಀᩘࡢ᫬⣔ิࢹ࣮ࢱࡢࣉࣟࢵࢺࢆᅗ2࡟♧ࡍࠋSnapshots࠿ࡽㄞࡳྲྀࡗࡓ᝟ሗࡀ

ᅗ㸰 ᇶ‽᣺ືᡂศ(Mapping ಀᩘ)ࡢ᫬㛫ኚ໬   Collinear approach at 330 Kᐃ㔞ⓗ࡟♧ࡉࢀ࡚࠸ࡿࡇ࡜ࡀศ࠿ࡿࠋ
ᅗ2࡟♧ࡋࡓ᫬⣔ิࢹ࣮ࢱࢆࣇ࣮࢚ࣜኚ᥮ࡋ࡚ࡑࡢἼᩘᡂศࢆồࡵࡓ⤖ᯝࢆᅗ3࡟♧ࡍࠋ 300 – 625
fsࡢ඲༊㛫࡛ࡳࡿ࡜ࠊ+&ఙ⦰᣺ືᡂศ " ࡟
ࡣࠊ#"ᡂศࡀぢ࠼ࡿࠋࡑࡢᙉᗘẚ࠿ࡽ"࣮ࣔࢻࡢ᣺ື ᗘࡣ⣙.࡜ぢ✚ࡶࡽࢀࡿࠋኚ
ゅ࣮ࣔࢻࡢ᣺ືᡂศ " ࡟㛵ࡋ࡚ࡣࠊ#"ࡸ
#"ࡀぢ࠼ࡿࡀࠊ᣺ື ᗘࡣఙ⦰᣺ືࡼࡾࡶ
పࡃ$.࡛࠶ࡿࠋ"᣺ື࣮ࣔࢻࡢ᣺ື
ᗘࡣ""ࡢᙉᗘ࠿ࡽ᥎ᐹࡍࡿ࡜.⛬ᗘ࡜ᛮࢃࢀࡿࠋࡇࢀࡽࡢ᣺ື ᗘࡣᐇ㦂⤖ᯝ࡜Ⰻࡃྜࡗ࡚࠸ࡿࠋࡇࡢࣇ࣮࢚ࣜኚ᥮ࢆ๓༙ࡢ
132-IV࡜ᚋ༙ࡢIV࡟ศࡅ࡚⾜࠺ᅗ 3 ᅗ㸰ࡢࣇ࣮࢚ࣜኚ᥮࡟ࡼࡿἼᩘᡂศ

࡜ࠊ๓༙࠿ࡽᚋ༙࡟࠿ࡅ࡚ࠊ"ᡂศࡀᑠࡉࡃ
࡞ࡗ࡚"ᡂศࡀቑຍࡋ࡚࠸ࡿࡇ࡜ࡀศ࠿ࡿࠋ

#"%"࡛࠶ࡾఙ⦰᣺ື࣮ࣔࢻ࠿ࡽኚゅ᣺ື࣮ࣔࢻ࡬ࡢ,95ࡀ㉳ࡇࡗ࡚࠸ࡿࡓࡵ࡜ᛮࢃࢀࡿࠋࡇࡢ,95ࡣᏙ❧ࡋࡓ┤⥺ศᏊ+&2࡛ࡣ୙ྍ⬟࡛࠶ࡿࡀࠊ+࡜&2ࡢ཯ᛂࡣ୺࡜ࡋ࡚ࡇࢀࡽࡢཎᏊࡀ୍ᖹ
㠃ෆ࡟㓄⨨ࡋࡓᖹ㠃ෆ࡛㉳ࡇࡿࡓࡵࠊࡇࡇ࡛࠸࠺"ࡣᏙ❧ࡋࡓ+&2ࡢ"࡜ࡣ␗࡞ࡿࠋ࠸ࡎࢀࡶྠࡌ
ᑐ⛠ᛶࢆᣢࡗࡓ㠃ෆ᣺ື࡛࠶ࡿࡓࡵࡇࡢࡼ࠺࡞,95ࡀ㉳ࡇࡾ࠺ࡿ+  ྠࡌࠊcollinear approach࡛ࡶࠊ20 Kࡢሙྜࡣࠊࡶ࡜ࡶ࡜ࠊ཯ᛂࡍࡿH ࡟ࡣศᏊ㍈࡟ᆶ┤࡞㏿ᗘ࣋ࢡࢺࣝᡂศࡀ࡯࡜ࢇ࡝࡞࠸ࡓࡵ࡟ࠊHCO+࡟࠾ࡅࡿኚゅ᣺ືࡢບ㉳ࡣ㉳ࡇࡽ࡞࠿ࡗࡓࠋ Collinear approach ࠿ࡽእࢀࡓ᪉ྥ࠿ࡽ᥋㏆ࡍࡿሙྜ㸦౛࠼ࡤ CO ㍈࡟ᆶ┤࡟ H3+ ࡀ᥋㏆ࡍࡿሙ
ྜ㸧ࡣࠊH3+ ഃࡢࣇࣟࣥࢸ࢕࢔㌶㐨࡜ CO ഃࡢࣇࣟࣥࢸ࢕࢔㌶㐨ࡀ㔜࡞ࡿࡼ࠺࡟ᘔࡾ㎸ࢇ࡛ࠊ⤖ᒁ
collinear approach ࡟᥎⛣ࡍࡿࡇ࡜ࡀศ࠿ࡗࡓ㸦⚟஭࣭⸨ᮏࡢ㓄ྥཎ⌮㸧ࠋᚑࡗ࡚ࠊCollinear approach࠿ࡽእࢀࡓ᪉ྥ࠿ࡽ᥋㏆ࡍࡿሙྜࡣࠊኚゅᡂศࡀᙉࡃ࡞ࡿࡶࡢࡢࠊ᭱⤊ⓗ࡟ࡣ Collinear approachࡢሙྜ࡜ྠᵝ࡞⤖ᯝ࡟࡞ࡗ࡚࠸ࡿࡢ࡛ࠊࡇࡇ࡛ࡣࠊࡑࡢグ㏙ࢆ┬␎ࡍࡿࠋaT. Hirao, S. Yu, and T. Amano, J. Chem. Phys., 127, 074301 (2007).

26 (2008).

cb

T. Hirao, S. Yu, and T. Amano, J. Mol. Spectrosc., 248,

H. Li, T. Hirano, T. Amano, and R.J. Le Roy, J. Chem. Phys., 129, 244306 (2008).

Chem. Phys., 104, 6081 (1996).

edT. Taketsugu and T. Hirano, J.

T. Hirano, T. Taketsugu, and Y. Kurita, J. Phys. Chem., 98, 6936 (1994).

Taketsugu, and Y. Kurita, J. Phys. Chem., 98, 6942 (1994).
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gf

T. Hirano, T.

Y. Kumeda, Y. Minami, K. Takano, T. Taketsugu, and T. Hirano, J.